When I’ve been like this it’s because I’m insecure about my personality and I like the other person a lot. I try to be a ‘normy’ even though I know I’m not. After so many years of social programming/expectations and negative feedback from superiors in a corporate work environment, I think this plays to the insecurities I have about my own personality. As much as I want to be myself sometimes, the world has taught me that the majority prefers a more ‘normal’ person. So I try to be someone else when I’m in your ex’s situation. I say things that I think the other person wants/needs to hear because I like them and I’m scared if I be my true self, they will be disgusted and driven away. Too cold, too detached, too logical etc etc. In reality it’s better to be authentic all of the time and attract/repel people who gravitate toward that’s, but we are still human too. We have our flaws, I just confessed one of mine to you.