Quick Answer: In monogamous relationships, getting STDs over and over again is often not because of cheating, but because of reinfection, untreated partners, or viral reactivation. To stop cycles, both partners must be tested and treated.
When Monogamy Meets Microbes
It’s a story told in whispers, DMs, and private forums: “We’ve been exclusive for years, but I keep getting herpes outbreaks,” or “My partner tested negative, but I tested positive again, how?” These moments feel like betrayal. But in reality, they often reflect biology, not bad intentions. STDs don't care if you're seeing someone. They do well in places where people can't see them, like when infections go untreated, follow-ups are missed, false negatives happen, or even when viruses that have been dormant for a long time come back to life.
In a study published in the journal Sexually Transmitted Diseases, over 40% of people who experienced reinfection with chlamydia or gonorrhea were in stable, long-term relationships where both partners believed they were monogamous. Sometimes the culprit was a previous infection that never fully cleared. Sometimes it was a misunderstanding of the window period, or a test taken too early after treatment. And yes, sometimes, it was cheating. But not always. That distinction matters.
Let’s get clear on one key truth: Monogamy does not equal immunity. Even within a committed, loving relationship, recurrence can, and does, happen. The question is: what kind of recurrence?
Reinfection vs. Reactivation: What’s the Difference?
Reinfection happens when a person clears an infection, then contracts it again, often from the same partner who wasn’t treated or retested. Reactivation, on the other hand, occurs when a virus like herpes lies dormant in the body and flares up again later due to stress, illness, or hormonal changes.
These two phenomena feel the same emotionally, but they’re biologically distinct. Here’s how that breaks down:
| Scenario | STD Type | Mechanism | What It Means |
|---|---|---|---|
| Reinfection | Chlamydia, Gonorrhea, Trichomoniasis | New exposure after previous treatment | Partner may not have been treated or was reinfected |
| Reactivation | Herpes, HIV, Hepatitis B | Virus dormant, then triggered to become active again | Not a new exposure, no one “cheated” |
Table 1. Understanding how recurrence works: reactivation vs reinfection.
This difference matters not just for your peace of mind, but for how you talk with your partner, how you test, and what kind of treatment or management plan you follow. It also dictates how you manage trust, both emotionally and biologically.
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Case Story: “I Got Chlamydia Again. He Said He Was Treated Too.”
Angela, 28, works in healthcare and had always been proactive about sexual health. When she tested positive for chlamydia, she told her boyfriend and they both got treatment, she assumed. “He said he took the pills, but I later found out he never picked up the prescription,” she recalled. “He felt fine and thought it was overkill.” Two months later, she tested positive again. “That second time broke my trust way more than if he’d cheated. It was like, you didn’t care enough to follow through.”
This scenario is heartbreakingly common. With bacterial STDs like chlamydia or gonorrhea, it’s easy to think antibiotics are a one-and-done. But reinfection rates are high, especially when partners don’t test or treat at the same time. The CDC recommends both partners be treated simultaneously, even if one tests negative, because of incubation periods and potential false negatives.
Angela's case isn’t about infidelity. It’s about miscommunication, poor medical follow-through, and assumptions. That distinction helped them rebuild. But not everyone gets that clarity in time.
False Negatives and the Myth of a “Clean” Test
One of the most misleading phrases in monogamous couples is “But I tested negative.” A single negative test doesn’t always mean someone is clear of infection. Every test has a window period, a gap between exposure and detectability. Testing too early after exposure or treatment can return a false negative, especially for chlamydia, gonorrhea, or even HIV. Add to that the human error factor, home test mishandling, missed follow-up labs, or misunderstanding results, and it’s easy to see how infection can persist under the radar.
Even in clinical settings, NAAT or PCR tests, while highly sensitive, can miss very early infections or fail to detect if swabs aren’t collected properly. And for viral STDs like herpes, many people test negative on antibody screenings because their immune response hasn’t developed enough antibodies to show up yet, especially if it’s a first outbreak.
So when a couple insists they’re both “clean” but one continues to have symptoms or test positive, timing becomes just as important as trust.
| STD | Best Time to Test | False Negative Risk if Tested Too Early |
|---|---|---|
| Chlamydia | 14 days after exposure | High if tested before 7 days |
| Gonorrhea | 7–14 days | Moderate |
| Herpes (HSV-2 Antibody) | 12+ weeks after exposure | Very high before 6 weeks |
| HIV (4th Gen Test) | 2–6 weeks | Moderate |
Table 2. Why timing is important: false negatives happen a lot when you test too soon.
Understanding this is crucial before jumping to assumptions about infidelity. A negative result may simply mean it was too soon to detect, especially if symptoms continue or reappear. The solution? Test again at the appropriate window, and always include both partners in follow-up care.
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What About Dormant Infections?
Many people assume that once an STD is treated or managed, it’s gone forever. That's not true for viral infections like HIV or herpes, though. These viruses can go into hiding and then come back, sometimes years later. It's not about cheating or being exposed; it's called reactivation. It's about the virus coming back because of stress, illness, hormonal changes, or a weak immune system.
Herpes simplex virus (HSV-2) is a textbook example. Someone might go years without symptoms, then experience outbreaks again, triggered by something as mundane as a cold or even intense emotional stress. These episodes can occur in people who’ve been monogamous for decades, and many aren’t even aware they carry the virus. Antibody tests can’t always tell when you were infected, only that you were at some point.
It’s not just herpes. Hepatitis B and HIV also have chronic forms where symptoms ebb and flow. For these, it's important to keep an eye on them, give them antiviral medicine when needed, and be honest with them. A flare-up doesn’t mean recent exposure, it means your body is still managing an existing infection.
This biological nuance is often lost in the heat of emotional reaction. A reactivated outbreak can feel like betrayal when it’s actually the body revisiting something it’s been harboring silently for years.
What If Your Partner Keeps Testing Negative?
Few things are more disorienting than testing positive for an STD, again, while your partner’s results stay squeaky clean. It makes you question everything: the relationship, your memory, even your sanity. But testing discrepancies are medically explainable. In addition to differences in window periods and testing types, there are also asymptomatic carriers. Some people never show signs of illness, but they can still spread infections. Trichomoniasis, in particular, often doesn't show any symptoms in men, which is why it often causes silent reinfections.
Also, not all partners are tested for the same infections. Clinics sometimes default to chlamydia and gonorrhea unless herpes or trichomoniasis is specifically requested. So one person may carry an undetected STD for months, or years, while their partner bears the clinical burden and emotional toll of recurrence.
These hidden variables are why mutual testing is critical, not just during relationship milestones, but when any symptoms reappear or test results come back unexpected. It’s also why you may want to retest even after “all clear” results, especially if symptoms persist. At-home kits can be a discreet, pressure-free way to do this, especially when in-person clinics feel too emotionally loaded.
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When to Suspect a Testing or Treatment Gap
If you and your partner have both been treated but keep facing recurrence, it’s time to look beyond basic assumptions. Did you both get treated at the same time? Did either of you resume sexual activity before finishing medication? Was there a confirmed cure, via follow-up testing, or was it assumed?
Antibiotic resistance is another growing concern. While rare, certain strains of gonorrhea and chlamydia have shown resistance to first-line treatments. That means even with proper antibiotics, an infection can linger or return. If you’ve followed all protocols and still keep testing positive, ask your doctor about a culture test to check for resistance, or opt for a full-panel lab test that includes less commonly screened-for infections.
This isn’t about fear, it’s about facts. And sometimes the fact is: recurrence isn’t your fault. It’s a gap in the system, a miss in communication, or a bug that outsmarts the drug. But you can still take back control.
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Can You Reinfect Each Other in a Monogamous Loop?
Yes, and it’s one of the most frustrating dynamics in sexual health. Even when couples are exclusive, reinfection can create an endless cycle if both people aren’t treated and abstaining until cleared. This happens most commonly with bacterial STDs like chlamydia, gonorrhea, and trichomoniasis. Here’s how it plays out: one partner clears the infection, resumes sex with the untreated other partner, gets infected again, and the loop repeats.
In this case, it’s not about infidelity. It’s about medical misalignment. This is why some clinicians advise treating both partners simultaneously, even if one tests negative, especially for high-recurrence infections like trich. This recommendation is echoed by the CDC’s treatment guidelines, which highlight the need for partner therapy and abstinence for seven days after treatment. Many don’t realize that reinfection can occur immediately if sex resumes too soon, even with condoms.
Maria and Theo, together four years, learned this the hard way. After testing positive for trichomoniasis, Maria got treated with metronidazole. Theo said his test was negative, so they resumed sex within the week. Three weeks later, she had symptoms again, and another positive test. This time, their doctor advised simultaneous treatment and a week-long abstinence period. The infection didn’t return.
What broke the loop wasn’t love or trust, it was medical coordination.
Testing Together Without Blame
It’s easy to say “just talk about it,” but when you’re facing an STD, again, it’s not that simple. Shame, anxiety, and fear of judgment can cloud even the healthiest relationships. The goal isn’t to accuse; it’s to align. Testing together can be a powerful reset, a way to reestablish trust, and to look forward, not backward. It also ensures that both of you are screened for the same infections, at the right times, using the right tests.
Some couples choose to test privately first, then compare results. Others opt for at-home kits to avoid awkward clinic visits. What matters is that you treat testing as a team effort, not a courtroom cross-examination. Recurrent infections don’t have to break a relationship, but secrecy and silence often do.
Normalize testing the way you normalize birth control or STI discussions early in dating. The more you integrate it into your health routine, the less shame it carries. And if it helps, reframe the conversation: not “Did you give this to me again?” but “Let’s make sure we’re both clear so this doesn’t keep happening.”
One act of shared testing can save months of doubt, and health complications.
When It Might Actually Be Something Else
Not every recurrence is caused by an STD. UTIs, bacterial vaginosis (BV), yeast infections, and even hormonal changes can mimic STD symptoms, especially in women. Burning, itching, odor, discharge, or pelvic pain can occur from multiple causes. And sometimes, aggressive antibiotic use can wipe out protective flora, making recurrent infections or misdiagnoses more likely.
If symptoms keep returning but test results flip-flop, or if antibiotics aren't working, it may be time to widen the diagnostic lens. Vaginal microbiome imbalances, hormonal shifts from IUDs or menopause, or even allergic reactions to latex can all play a role in mimicking STDs. In these cases, insisting on a full panel and vaginal pH assessment may give more answers than another round of azithromycin.
One Reddit user described recurring symptoms that turned out to be from a new soap her partner had switched to. Another, a man in his 30s, had repeat burning and discharge that was ultimately linked to undiagnosed prostatitis. The point is: not all repeat symptoms are STDs, but ruling that out is the first step toward real answers.
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Let’s Talk About Cheating, for a Second
This part is hard. It’s possible that recurrence points to a new exposure, and that exposure may have happened outside the relationship. But that’s not a medical diagnosis. It’s a relational one. And no test can prove timing, intention, or truth. What medical facts can offer is a starting point: this infection is present. Now what?
If cheating is a fear, acknowledge it, but don’t treat it as the only explanation. Use the recurrence as a reason to check timelines, clarify testing, and protect both of you moving forward. It’s not about catching someone in a lie, it’s about catching a silent infection before it causes harm.
Infidelity is emotionally devastating. But so is medical miscommunication. Take care of both, in that order.
FAQs
1. Can I really get an STD again if we’re both faithful?
Yes, and it sucks. But it’s not always about cheating. STDs like chlamydia or trich can come back if one partner was never fully treated, or if you started having sex again too soon. Monogamy doesn’t make you immune, it just narrows the source.
2. What’s the deal with herpes flaring up after years?
That’s classic HSV. Herpes is a lifelong virus that chills in your nerve roots and flares when your body’s stressed, emotional drama, a bad cold, your period. It doesn’t mean someone new gave it to you. It means your own virus just clocked back in.
3. Why do I keep getting chlamydia even after taking antibiotics?
Usually, it’s because your partner didn’t get treated too, or they got reinfected elsewhere and passed it back. It's not always betrayal; sometimes it’s bad timing, poor follow-up, or just... forgetting to finish the damn pills. Real life is messy.
4. My partner tested negative. So why did I test positive, again?
Short answer: test timing. Long answer: window periods, asymptomatic carriers, and some STDs being missed on routine panels. False negatives happen, especially if they tested too early. And some people carry infections like trichomoniasis without ever feeling a thing.
5. Is it possible we’re just passing it back and forth without knowing?
Totally. It’s called “ping-ponging,” and it happens when one of you clears the infection and the other doesn’t. Then you get it again, they get it again, it’s a bacterial game of hot potato. Coordinated treatment is the only way out.
6. Do condoms fix this?
They help, but they’re not a magic shield. Condoms cut down risk for chlamydia, gonorrhea, HIV, and more, but they don’t fully block skin-to-skin spreaders like herpes or HPV. Plus, if you use them inconsistently (ahem, "just at the start"), you're leaving the door open.
7. Could I be mistaking something else for an STD?
Yep. Not every tingle or itch is an infection. Things like yeast, BV, hormonal shifts, allergic reactions (hello, new lube), or even tight clothing can mimic symptoms. That’s why testing matters, guessing gets you nowhere fast.
8. We both took the test. Should we take it again?
Yes, especially if one of you had symptoms or a positive result. Retesting a few weeks after treatment helps confirm the infection’s actually gone. It’s not about paranoia, it’s about peace of mind. Better a second test than a third outbreak.
9. If I got an STD, does that mean they cheated?
Not necessarily. We know that’s the first fear, but biology is trickier than betrayal. Reactivation, untreated past infections, or test timing issues can all play a role. That said, if trust is broken, it’s okay to deal with both issues: medical and emotional. Just don’t confuse the two.
10. How do we talk about this without it blowing up?
Lead with curiosity, not blame. Try: “Can we figure this out together?” or “Let’s both get retested just to be sure.” The goal isn’t a witch hunt, it’s health. Use at-home kits if clinics feel too tense. And remember: taking care of your sexual health is a team sport.
You Deserve Answers, Not Assumptions
Recurring STDs in a monogamous relationship don’t always point to infidelity, but they do always signal something important: a need for shared testing, honest communication, and treatment that includes both partners. Whether it’s chlamydia reinfection, a herpes flare-up, or a hidden infection missed the first time, the solution is almost always medical clarity, not blame.
If your relationship matters, so does your health. Don’t settle for assumptions or guesswork. Get tested together, talk openly, and close the gap between symptoms and certainty, because monogamy shouldn’t come with mystery symptoms.
How We Sourced This Article: We combined current guidance from leading medical organizations with peer-reviewed research and lived-experience reporting to make this guide practical, compassionate, and accurate.
Sources
1. CDC – Sexually Transmitted Infections Treatment Guidelines
2. Planned Parenthood – Herpes: The Basics
5. Herpes – STI Treatment Guidelines | CDC
6. CDC: Retesting After Treatment to Find New Infections
7. Sexually Transmitted Infections Treatment Guidelines, 2021 | CDC
8. How to Find and Treat Sexually Transmitted Diseases (STDs) at the Mayo Clinic
9. Sexually Transmitted Infections: Recommendations from USPSTF and AAFP
10. Sexually Transmitted Infections – StatPearls | NCBI Bookshelf
About the Author
Dr. F. David, MD is a board-certified infectious disease specialist focused on STI prevention, diagnosis, and treatment. He blends clinical precision with a no-nonsense, sex-positive approach and is committed to expanding access for readers in both urban and off-grid settings.
Reviewed by: Alexandra Tran, MPH | Last medically reviewed: February 2026
This article is for informational purposes and does not replace medical advice.
