I do not know how to quote but in reply to Arch's one word question, "Force?", I have an answer. At least for men I know and my own experience living as a male - If a male acts "like a female,"* which includes liking men too well, they are likely to be teased and harassed, sometimes physically assaulted, so I think force is an appropriate word. Of course the internal pressure we put on ourselves to avoid social pressure is the worst "force" of all.
includes liking men, the wrong colors, or foods, showing feelings, being considerate or willing to compromise, liking the wrong music or movies or clothes, being nice to women not for sex, and so on. Not every point for every man, but a lot. very restrictive.