The basics of any relationship are to support one another, to gain comfort from one another and to keep each other happy. Love is bringing out the best in one another.
In a healthy relationship, the couple will work towards the relationship equally.
Healthy relationships consist of a system of checks and balances combined with equality, individually and compromises.
Usually there is little compromise, forced inequality and your individually is taken away from you.
In an abusive relationship, one partner uses these goals against their partner as a way to manipulate them into doing what they want.
Abusers often use excuses such as:
"If you love me you would..." or
"You have to make sacrifices for a relationship" or
"it would really make me happy if ..."
Using these phrases does not come across as demanding and therefore can be hard to distinguish as what they really are, this is a way of taking advantage of you.