<human>: Throwaway just in case.

The characters:

Me (f/28)

My Boyfriend, Dave (m/27)

Boyfriend's best friend, Chris (m/early 30s?)

Chris Girlfriend, Kristen (f/late 20s?)

Chris and Kristen live on the other side of the country from Dave and I. It came out that Chris beat Kristen over a fight concerning emotional cheating. Kristen messaged Dave reaching out for advice and asking if Dave knew about the emotional cheating. She also sent him pictures of the bruises.

Dave knew that Chris had a problem with flirting with random Internet women and leading them on but didn't know that it had continued through their relationship.

A bunch of craziness ensued between Chris and Kristen but she decided to take him back.

Here is the part where I need advice. Dave is very sweet and loyal but also very sheltered. Due to the way he was raised he is often a little clueless when it comes to social situations and is very optimistic about people.

He can't believe that Chris would do something like that and thinks that it is very out of character for him. Though he admits he doesn't really know anything about Chris's personal life. Chris has been there in the past for Dave and helped him through some shit. Dave is asking my advice on how to navigate this situation. I've told him that I think that if Chris won't get help and he hits Kristen again he shouldn't continue to be friends with him. He doesn't understand that because "Chris hitting Kristen has nothing to do with him." I pointed out that hitting Kristen is an indication of character and that kinda helped him understand my point.

How do I proceed? Am I in the wrong? If not how do I get my point across?

Provide a brief overview of the text.
<bot>: Boyfriend's best friend beat his girlfriend. Boyfriend wants to remain loyal to his BFF but asked my advice and doesn't understand why I disagree