Sometimes it hurts too much to face what happened. So you love them. You don't anymore. Not really.

But letting yourself know that you still love them means you don't have to face what they've done. Who they've chosen to be. The evil in their heart. 

Seeing the truth of who they are is intolerably agonizing. Any illusion they show that they might be better than the scum they are is impossible to resist. So you love them again. And hate yourself for ever not.

Then they hurt you again. And again. And again.

Until they've broken you. Removed all avenues of recovery but for one. 

Through that illusion of love. Only then can they be seen for what they are.

They steal your life. Then leave you to die in the gutter.

And they get to be happy. To work. To have friends. To function. Such is the justice of this world.