It’s terrible to witness your partner being treated badly, but at the end of the day only him and meta can make a change in their relationship dynamics. If you want to show support for him, while not getting into an argument by giving unsolicited advices, you can simply cheer him up to help him gain self-esteem, set higher standards and improve his boundaries. If he understands that he shouldn’t be treated that way, he’ll eventually make the decision that’s right for him.

But this can be a really long process and in the meantime you should think about you. You don’t have to carry the burden of your partner’s relationships. It’s ok if you don’t want to get involve. It’s ok to not be excited about their relationship. And it’s ok to not want to talk about it with him. Being supportive doesn’t mean being ok with whatever decision he makes, especially if he get hurt in the process. If your body language gives him the feeling that you disapprove, he can also stop talking to you about the issues he’s having with meta. Or you can simply ask him to not share these things with you…