I'm going to tell my roommate I was worried he was being abused by his live in gf
Why do you want to bring up something private?
I don't want to see my friends being abused by someone.
If it's for the right reasons then yes, it's good to be concerned about their well being. You should assist him to police if the problem gets worse.
Some one needs to take a stand.
Totally! Abuse is never ok and I applaud you for standing up against injustice.