however, the last few times he didn't O, which then makes me insecure about myself and that whole validation thing.
Maybe he didn’t O because he MB the night before, or maybe that morning. In either case, it has nothing to do with you, and unless he said something or did something to imply you were responsible for his not O’ing, then your thoughts are all about your validation.
I’m with Lil that there could be some insight here for you, especially since you two are “see-sawing” back and forth between LD and HD, between grasping for control and going into P/A mode as the other grasps for control. See-sawing back and forth is also about seeking validation. IMO, being a strong, dominant, independent, type of woman (and I am not saying you are all this, but you do have some of it in you) is about protecting yourself from lack of validation. So, yeah, I also think there is a lot to look into those feelings of rejection.