Sometimes the person who does not have the upper hand loves the other person more and the person with the upper hand knows it. He or she sometimes take advantage of that. When or if you find yourself it that position, don't allow yourself to be taken advantage of. Respect your self and that person will respect you as well. Never allow yourself to be any sort of victim.
People have different takes on the same things. Some view a relationship as a 50/50 thing but some consider themselves superior. Culture also plays a role in this because traditionally, men had more than a half share and the same continues to date. It just is impossible to change people's ways of thinking.