My [M19] friend [F19] hates a guy [M19] I hate but she used to like him

My friend (let's call her claire) used to like this guy that I have had multiple altercations with. Me and (let's call him Isaac) have never liked each other since the day we met, but all three of us live in the same university accommodation so we see each other every day. Claire talks about how much she hates Isaac all the time, but the fact that she still talks to him makes me think she cares about him. I think she deserves better but I'm not sure wether to tell her and risk alienating myself if she does end up with him or trusting her statements and believing she hates him.

TL:DR My friend likes A guy I hate. Not sure how to proceed