I had something similar happen, and I have no explanation. I was with someone for 9 months before he started to get symptoms and got checked out. We were 18, he had been a virgin before our relationship, and I know I did not sleep with anyone at all when we were dating. Because I had before, I actually got a negative test early on- so I was clean ~8 months before. I KNOW him and know he did not cheat on me. I know I am just a stranger on the internet, and I can't prove anything at all. There is not a question in my mind I was the only person he had ever had sex with- and it took him over a year later to move on to someone else. I know perfectly well I had been tested clean and did not sleep with anyone else. Yet, chlamydia. Even a decade later, he asked me to tell him if I cheated because he still couldn't understand what happened otherwise. I didn't. I have no medical explanation for this whatsoever.

I was working at a public pool, and often wet in a bathing suit, using wet public facilities? But that's just urban myth, right? I feel like I'm an idiot saying any of this. It's absolutely what happened.

I think if your husband is unfaithful, you'll come across another instance or other evidence.... but maybe you know in your gut either way? I'm sorry to cloud the waters.