I don't know if this qualifies as a disorder, but I purposely fantasize about how my relationships will end in order to "prepare for the worst." My father cheated on my mother and, when I was young, I promised myself I'd never get hurt that way and never be so unaware as my mother was. By telling myself this and practicing my breakups, I've probably destroyed numerous relationships. I've basically practiced being suspicious and never been able to trust anyone 100%. I do not want to do this, as I'm well aware of how damaging this is, but it is a defense mechanism that's been in place so long, I don't know how to make it go away. I try to distract these thoughts by focusing on my partner's real behavior (rather than my fantasies) but I slip too often and usually end up in a negative place of my own creation. Honestly, I practice how the conversation will go if I ever discover a partner cheating but, in actuality, I've never discovered that a partner ever HAS cheated...I don't do any of this with my partner...it's all in my mind....but it makes me suspicious of otherwise trustworthy men....I desperately need a way to retrain my brain....because I want to trust and love without fear any more. Hope this makes sense.