>>42457756 (OP)
It's because of "Might Makes Right" mentality. Regardless of what a female wants or doesn't, if she lacks the strength to enforce her own will, than her desires get overwritten by those of others, in this case, the male.
Since the male has the strength to enforce his desires, than those must be the correct desires to enforce and the female conforms to his reality, thus enjoying the reality he created- them having sex.