Guy gets STD tested after last sexual experience, eventually gets new girlfriend. 8 months later, he suddenly develops symptoms of chlamydia and girlfriend tests positive. r/relationships immediately goes on defense for the girl.

http://np.reddit.com/r/relationships/comments/1e0tmx/my_so_24f_gave_me_30m_chlamydia_what_now/

Hmmm... Let's see. What's more likely:

That a guy and a girl in a relationship both had asymptomatic chlamydia for 8 months and the guy coincidentally develops symptoms at the same time the girl accidentally finds out at the doctor she has chlamydia...

Or the girlfriend cheated, found out she had chlamydia from it one way or another and tested to confirm, leaving her no choice but to tell her boyfriend and hope he buys her bullshit story.

Hrm. This is a tough one.