[psusue]

I mean I'm still best friends with my ex's friends, but that's because we were all in the same friend group. I think you can tell a lot about a person though about how they treat their friends though. For example if they aren't the best communicators with their friends/roommates, you can bet they won't be with you once the honeymoon stage is over, etc. You can also tell a lot about a person by how they act to and with their family members, and conversely they can tell a lot about you with yours.

On the whole I don't think you need to necessarily be best friends with all of their friends but it certainly helps. And I think you absolutely need to have a baseline of respect for them, even if you don't like them, because otherwise it would be hard to sustain a relationship with your SO. Especially if you're on a long term/marriage track, these people are obviously important to both of you and it makes life a lot easier if you all can at least tolerate one another, IMO. And if you like each other/enjoy spending time with one another, so much the better, I think.