I think it just seems that way to you because you're a guy, and because the women you find the most attractive have so much demand that they can become spoiled and very demanding.

Men don't have to be anything, and neither do women, but when you're young this perspective traps you and you feel you have to play the game. That's actually what a long term relationship is, you can just be yourself, and someone likes you for, and despite, who you really are.

People who expect and demand a lot from their partner are immature and don't understand that that's not how you build a stable relationship. There's only so much you can ask someone to give you before either they crack or you get bored.