My (19)f boyfriend (20m) thinks his friends cheating on their SO's is acceptable behavior

My friend was telling me about how she's friends with a couple where the girl is cheating on the guy. I said she should tell the guy about this and she refused to because she wanted to be loyal to the girl, who she was friends with first.
Anyway, I was ranting to my boyfriend (2yrs) about this and then he said he also wasn't sure if he'd tell a friend's SO if they were cheating. Some of his friends have girlfriends, and my BF knows them casually but isn't very close with them. He said that he really wouldn't want to lose a friend to help someone he barely knew so he'd probably keep his mouth shut. He did say that if he was close friends with both of them he'd probably say something. Now on one level I guess I understand not wanting to lose a friend, but I'm also concerned now that I know he thinks cheating is at least tolerable, if not acceptable. He says he knows what the morally right thing to do is but couldn't go through with it. I'm not close with any of his friends, but we've hung out before and if my bf was cheating on me I'd definitely want to know.
I asked my bf if he'd still be friends with someone who was homophobic or racist and he said that as long as they were good to him, he wouldn't be super picky about his friends. But he also says he doesn't hold his friends to the same standards he applies to himself or me. This just.... rubs me the wrong way, I guess. I don't think I could be good friends with someone who held moral views so different from mine. I'm not sure how to feel. It's not so much that I think my bf will cheat on me, but that he's okay with the concept of it and wouldn't necessarily condemn it coming from the people close to him. Is this something to worry about? Or am I overreacting?
tldr; boyfriend says he probably wouldn't tell a friend's SO if they were cheating. This makes me feel like he thinks cheating is okay. Overreaction or a red flag?


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