That's human for you,always self centered and selfish they want everything for themselves but sometimes never reciprocal.
Humans a lot of times forget that life operate on the principle of give and take and to get everything going right almost all gestures must be reciprocated.
People are lovers of self as recorded in the bible.Most people are in a relationship for what they can get from their partner, it always about me and it seem all one sided.One person will provide love,money, Care, patience,peace and what nots in the relationship and the other person brings nothing to the table apart being a leech and sucking the other partner dry psychologically,emotionally, financially and otherwise.
I don't only love but be loved too.it should be balanced that way.