He was her boyfriend who made out with her cousin right in front of her. She loved him but felt betrayed when she saw that then slapped his ass. At least from I remember. Afterwards she ranaway from that shitty house and family and took the name of wendy waltz.
I know the ex did nothing so far (since they've already broken up and she got to slap him and all, well she could've certainly done more since he cheated?) but a part of me wants ML to just find an excuse to demote him