My sister's boyfriend is a di*k!

Okay so I have a twin sister and her boyfriend has been nothing but trouble since day one. (it's been almost 5 years of dealing with his sh*t) I realize that it's partly her fault for putting up with it and going back to him when he breaks up with her...

but why won't they just end it? I know I can't get in her relationship but tell me if this is normal. He's cheated on her 3 or 4 times, Breaks up with her when one of our family members dies so he doesn't have to go to the funeral, won't go around our family, breaks up with her around holidays so he doesn't have to buy her anything... he's never bought her a gift in 5 years! He tells her he doesn't want to marry her or be with her and he'll totally ignore her... but she goes right back to him. It's like she stalks him into getting back with her. I'm so sick of dealing with their break-ups and drama. Is this normal? and why does she keep getting back into that mess?!?!? She's beautiful and can do so much better than him?

Sounds like shes is attached, it must be things he says to her in private, if anything he'll get whats coming to him, karma seems to be real, it will catch up, if she cant see he's such a bad guy then its mostly her fault, sorry to say. Tell her how you feel about it, and ask her to think about it, REALLY think hard and long about it.