@Testament
It sounds like now is a really good time for your friend to learn that in healthy relationships, you don't need to Do Exactly All of the Things Always and Forever with your partner. Like, it's legitimately better for both of you if you don't share all of the same interests/hobbies/social circles and that you don't necessarily have to be forced to choose between your boo and your besties.
Example:
@insomniac7809 has a super shitty, unpredictable calendar because he works retail. It is often difficult for him to make plans in advance, so scheduling social activities is hard. I have some things where if he's off that night and going out -- SCA events, bowling league -- I will include him every time, because he knows those people, gets along with them, and it's a group event.
I also have my two best girls, who both adore him. But. But! When we go out, it's frequently a "ladies night" kind of vibe. I will only invite my husband along after asking my friends if its okay and even then, it's when we're doing things like going to the movies or going to one friend's house when I know her husband will also be there for him to chill with. When we're getting together for our annual Christmas dinner, grabbing drinks, having a life event gossip/vent session, or celebrating our strangely close birthdays.... he doesn't need to be there. At all. It would be awkward and weird.
It should be okay for your DM to be able to have TT nights with his just his friends. It should be okay for you to ask. It is not okay to be ass about it or frame it as "her or us" when you have the option of going with, "Hey, man. I noticed your girlfriend seems pretty uncomfortable with some of our views, some of us have been uncomfortable with her behavior, and you're left in this awkward in-the-middle position that must feel awful. Since we don't all gel, maybe we can do our TT with just us and you can do X, Y, or Z with just her?"
That's not a comment on her being a shitty person, pressure to sever a relationship, or being melodramatic. It's just acknowledging that you guys don't mesh and that probably sucks for him, so you want to find a solution that leaves no one feeling strained and uncomfortable. You never know. He might even be relieved to have someone give him a reasonable out without anybody bailing, crying, or shooting each other awkward looks.