If it ain't a real thing, it should be. Seriously. Bad relationships abound and, if we're lucky, they end. The aftereffects of them, though, can last for years beyond the final goodbye. (Setting aside those that won't accept goodbye as final, and who may perhaps stalk you afterwards.)
These bad relationships effect the way we handle new relationships. Hell, they can ruin a burgeoning good relationship. This, my friends, is caused by Post Traumatic Relationship Disorder.
Let's say you have an ex-person who constantly turned everything you said against you. You step into a new relationship on edge, waiting for something you said to become fodder.
Let's say instead that you were with someone who constantly lied to you. Now, you doubt everything a potential new mate says.
Or what about the ex who stole from you? It kind of makes you watch every move your next love makes - you know, just in case.
These new mates haven't done a damn thing wrong, but they get painted with the brush dipped into our experiences.
Hubs referred to all this as boxes in our warehouse. We opened some of them up and shared them when we were courting. Then we closed them back up, sealed them, and shoved them back in there. They're out of sight, but, for me, they're never really out of mind. It's been twelve years and I can still hear the voices of relationships long dead whispering things in my head when I'm not guarding against them.
So, what do you do? I'm not exactly sure. I try to ignore the memories as best I can. Being in a good relationship for a long time helps. And when the demons crawl under my skin, I try to remind myself that those old experiences are not applicable to anything now.
Hang in there, folks. It does get better. And, remember, you can always kill them in your writing - even if you only write it for yourself to read. That helps, too. ;o)