First of all, almost everyone is bisexual to some degree. You first need to question yourself whether you feel more attracted to women, more to men, or about equally as much. If you feel more attracted to men, these times it would be stupid to still marry a woman and live a forced, fake life (and eventually divorce or stay unhappy). I don't know whether you're friend is more straight or more gay (which he then tries to deny and cover up by marrying a woman), but it certainly looks like he won't allow himself to have a full relationship with another man…