I’m going through the same thing. I’ve mostly tried to be mindful. Know myself and recognize when I’m pmsing. Try to take a step back when I think thoughts like “he’s going to bang someone else and doesn’t actually care about me.” I just try my hardest to be present and know that these feelings are temporary. I try hard not to contact him at all when I feel this way but when I just can’t help myself I try to be honest with him and just straight up tell him “I feel like arguing with you and I feel like I could use some reassurance.” I’ve learned from experience that doing that is so much more productive than starting a fight based off of situations I’ve mostly created in my head.