If by "weak" you mean shallow, I think I basically agree. It sounds like you are describing men who are attracted only by a woman's looks and interested only in sex. Those men will sometimes try to get what they want by spending money--meals, drinks, gifts--hoping the woman will feel obligated to sleep with them. Some equally shallow women are willing to take advantage of men like that or even string them along. You can call it "friend zone" if you like, but it obviously has nothing to do with friendship on either side.