I know, I gotta think about them more... I just have so many stories in-progress at once, the vampire hunters have kinda been on the back burner. :')

She broke up with him after about two years together. She'd known for a few months that he was abusive, but he was becoming so violent and unpredictable that she was scared to confront him. Eventually (with much convincing and support from some friends) she did break up with him. It wasn't pretty (she probably would've been badly hurt if her friends hadn't been there). She actually left school afterwards to avoid running into him again, and began to focus on her hunter training instead. As far as I know, she never spoke to him again.

(I don't think the boyfriend knew Sandra was from a hunter family. Even if he met her family at some point, they probably kept it secret.)