I (26M) am 5 months into a relationship with my girlfriend (26F). In the early stages I really liked her qualities but recently I have come to discover a personality thorn I cannot remove: she is a little selfish and judgmental. It's subtle so I have often moved past it, but often hearing her judgmental attitude saps my energy. She is specifically judgey about prestige, clothing, and other people's quirks. She also rarely smiles when she is with me, and when I asked her why, she reacted by emotionally receding, deadly cold. The things that seems to connect us is her commitment to me emotionally, the emotional trust we have established, and incredible sex. I have told her that her attitude and tone bother me and I wish she could see differently about other people, but she has not changed. I also don't like her friends because they are similarly judgmental and gossip in a judgmental way.
That's when I reconnected with a situationship (24F) who was a housemate for 3 weeks. We had and still have incredible chemistry. She is really kind and smart (super fun and imaginative) and a great communicator. After talking she said she wanted to reconnect; she acknowledged that we had good conversational chemistry together, and she thinks I'm funny. When asked, her romantic situation was complicated and she said she doesn't know what she wants. She sad she also didn't want to hurt anyone. She said she wanted to be friends, so I said let's be friends. Somehow that has made her open up, be flirty, and now she is making future plans with me for the summer (all date-like). I have not moved these plans forward as I know these would be boundary crossing.
I don't want to emotionally cheat because I value the emotional trust my gf and I have established together. However, I do think the values piece is chafing me (and probably her as well). I also know this situationship is risky but I also want to have fun with her and explore this relationship (go to concerts, museums, altered mental state experiences). Is there a world in which I do these activities with my "friend" and remain in my relationship? Or should I breakup with my gf and then do these activities with my friend? Or should I double down with my gf and try to workout the values clash more thoroughly (which seems really hard and requires a lot of patience)?