My current girlfriend (let's call her Anna) and I work together at the same company, but in different departments. She started a little earlier than I did. She has a coworker (Sophie) in her department whom she gets along with well, but their relationship has never gone beyond work. After a few months, this colleague told her that she liked her and felt drawn to her, but since she has a boyfriend, she doesn’t want to do anything about it—she just wanted to tell her. This messed with Anna’s head a bit, and she realized it could turn into something more. Shortly after that, we started dating, and Annie cleared things up with Sophie. I, however, don’t really like Sophie and have felt uncomfortable around her from the very beginning—we have different lifestyles, different values, and she’s broken our trust (she spread a rumor at work that there’s a new couple at the company). Now, all of a sudden, their friendship has started to extend beyond work, and the idea of a group get-together has come up. Am I an asshole for not wanting to go, and even more so for not wanting my girlfriend to go there alone?
I should add that I’m new to the LGBTQ+ community.
My girlfriend has relationships with people she used to have a connection with, but these are long-standing friendships and I don’t have any feelings of that nature toward them. I trust her and I know she loves me, but I feel very insecure about her relationship with Sophie.