From how I understand it, as a rough approximation there are 3 categories of men that women view. Guys they will never have sex or be in a relationship with. Guys who they will have sex with, but not be in a relationship with and guys who they will be in a relationship with, but not just have casual sex.

Guys who they will have sex with, but not a relationship are typical very good looking types. The infamous 20% number that gets tossed all around here. These guys are very attractive to where women are fine just having casual sex with and thats it, but will settle for an average looking boyfriend if he has other good qualities like compassion, intelligence and humor.

Men on the otherhand are different. Men place a higher standard of looks on a potential girlfriend than a fuck-buddy. From my personal experience and that of looking at Men around me, having no strings attached sex with an unattractive-ish girl is fine if the opportunity presents itself, but a relationship? Forget it. If im going to be in a monogamous long term relationship, then she needs to at least be average looking and average weight. This is the only person im going to be having sex with and so men need to ensure this parameter is met or no girlfriend status will happen.

Of course, men also want to have sex with very attractive women, but as mentioned on here on many occasions, this isn't always a reality and many men must simply take what they can get or be left alone.

TLDR: Women will have casual sex with hot guys and settle with decent looking boyfriends while men while have casual sex with unattractive girls, but be in relationships with at least average looking girls.