They both need help. There was an article in today's paper with Oprah warning Rihanna that he will do it again, and with some DA comparing him to OJ Simpson. The thing is, the young man needs counseling. He's the lowest of the low right now, but doesn't have to remain that way. Hopefully he can change, and hopefully he will. Sure I think Rihanna should leave him, but sadly, most abused women take it for quite some time before they go. Not to mention that it has been reported that she's been very loose with her hands in the past. If that is true then she needs help as well, and it would explain why she's not thinking of leaving. She obviously believes herself that violence is a solution if she's taken swings at him. It's just all too sick really, and they both need help, or even if she leaves she will run into another abuser, and he will just find another woman to abuse.
ETA-I doubt if this is the first incident. These things don't usually start out with the type of beating that was described here. Hopefully someone will convince her that she needs therapy as well.