HIV transmission is 18 times more likely with receptive anal sex than with receptive vaginal sex and 69% of the HIV positive people in the USA are active gay men.
So yes, being a homosexual man is a huge risk factor and probably more significant than being in an open relationship, cheating on your partner or performing unprotected sex unless you live in Sub-Saharan Africa.
The risk factor in the US is "man who has sex with men", not "gay man". Factors can combine: e.g. "gay virgin" is a lower risk factor than "straight + multiple partners".
So yes, being a homosexual man is a huge risk factor and probably more significant than being in an open relationship, cheating on your partner or performing unprotected sex unless you live in Sub-Saharan Africa.