O.C.D.D (Obsessive Compulsive Douchebag Disorder)
You're completely obsessed with a lover who is a total mess. You take them back every time they break up with you, even though they're clearly the worst person you could ever date.
'He broke up with me, but I still took him back.'
'He called me a loser, but I still believed in him.'
'He said he'd never come back. I believed him.'