My sexual partner just told me that he recently tested positive for a STI. I know for a fact that I didn’t infect him because I am not comfortable with having more than one partner at a time. He claims that I am the only one that he’s been with... and that the last person that he had intercourse with prior to me was in almost a year ago... Now, when I look up the STI it tells me that most symptoms go unnoticed and that an individual sometimes won’t know that he has an STI. Should I believe that I am the only girl that he’s been seeing? Or did he recently contract the infection by having more than one sexual partner?