Is this simply evolution in action? Why seek an emotional bond with someone who can impregnate you when you can establish an equally solid bond with someone who can’t? sounds practical enough. We can debate until we are blue in the face whether that is good or bad. As a a matter of fact, the idea of engaging in such an act might be strongly detested by some women. The researchers found that bisexual women, compared to lesbians and heterosexual women, were evaluated as more confused, promiscuous, non-monogamous, neurotic, extraverted, and open to experiences.
Men have gotten so much cultural c**p put on them that even if a man does have some sexual attraction to guys, they would never say it. I’ve not heard of any other examples in the animal kingdom whereby males (or females for that matter) actively engage in activities (much less spend all of their time) which reduce their chances of reproducing.