I’m scared my bf will cheat on me. I feel like he lacks boundaries. He has this friend who he’s really close with, and she’s currently going through a breakup. Her ex and her have joked that my bf is basically in a poly relationship with them because he’s always around them and involved in their relationship. They also made a promise that if they ever broke up, my bf would date her, and my bf has dangled that joke in front of me before. I know they’re probably joking, but it makes me feel really powerless and insecure. Now he’s going to be spending more time with her to help her through the breakup, and I don’t know if I trust him. They’re online friends right now, but they’re meeting in October, and I’m scared about what could happen when they meet in person. I’m scared they could end up doing something romantic or sexual, even though I don’t actually know that they will. I don’t want to stop him from supporting his friend, and I know she’s going through a hard time.