Interesting to hear you say it, because my experience is very opposite. For many men, sex feels like much more of a woman's requirement in the relationship than a man's. I've had many a conversation with other men ruefully bemoaning the difficulty of becoming friends with a woman if sex isn't on the table. (Straight men---I don't think it applies to gay men.) The exception (among men I know) is friendship that survives the end of the romantic relationship. I'd say the majority of my friends are ex-girlfriends, but I can only think of one woman I've been able to become friends with without sex. And that hardly counts because of a huge age difference.