I keep having sex dreams about my boyfriend’s best friend

So I’ve known my boyfriend’s best friend for a long time and we had come close and I confessed my feelings for him. He had just gotten out of a relationship that left him in a bad place so he said nothing would happen. Everything continued as normal and we are still good friends but I had started dating someone who happened to be his best friend. It’s almost been 6 months with him but I can’t stop thinking about the other guy and having dreams about him. Idk what to do