I'm female, but I had no idea until after I'd had sex with bisexual men that the HIV risk was much higher than from sleeping with straight men. I used condoms anyway, but I was pretty shocked to learn about it. I still date bi men*, but I'm much stricter about making sure they've had STI tests than I used to be.

*My main social group are the UK bi/poly community, so two out of three of the men I've dated in the last few years have been bi.