I have seen a lot of people here claim that most women are into "casual" sex, and subsequently go on to make claims about how women are more trust worthy due to that. Or, that how women simply don't take up opportunities to cheat or have more sex because they aren't into casual sex.

The problem here is, "casual" sex is a male concept. Men are the one's who are more validated or excited by the idea of sex coming with very little investment in the woman or a short time after meeting her. This also applies to the idea of one night stands or hookups. A lot of male fantasies or role plays revolve around non-relationship settings or hence "casual" settings, such as getting to fuck your nurse, your secretary, fucking a girl in the club bathroom, etc.

Women, on the other hand, don't value sex based on it's immediate availability. They are not more excited or validated based on how soon they can get a guy to have sex with him. Women are just simply focused on the feelings and chemistry they have with men. Once the chemistry or tension they feel about a guy builds up enough, they are ready to have sex.

Women aren't opposed to sex not long after they meet a guy, they are only opposed to sex when they don't feel the chemistry or lust for it. Women say they don't like "casual" sex because it's a male concept, how quick you can get laid is not built into what a female yearns for with sex and pleasure.