Because it is. History context matters and we are basically told this since we are little girls. We never are good enough. We need to settle or we'll become spinsters and there is nothing worse. Your academics succes, get a good job, high wage, your own home? No, nothing of that would make you worthy if you don't catch a man. And findind a man to marry is all about looks. We "need" to be beautifull and "likeable". Don't talk to much, don't be too intelligent, laught at his jokes even if they are not that funny, make him feel important...

Of course, by the time we become teenagers and young women, we are feed up of that narrative. And many young women turn the table on men. It seems they resent the even field.