I too was constantly accused of cheating throughout my first marriage. Not for any reason other than her suspicions... it was exhausting! She also took offense to the fact that I'm not the jealous type. Some dude would hit on her and she'd be upset it didn't make me mad. I'd respond "Are you interested?" "Well no!" "Then why should I be worried or upset. I trust you." It took me far too long to realize she suspected me because she knew she'd cheat on me if the situation were reversed and she figured everyone was like her.

During our divorce our court-ordered psychiatrist said he believed she suffered from some psychosis but would need more time to properly diagnose it. Since then I've come to realize her behavior is well-described as a vulnerable narcissist, and combined with her alcoholism and paranoia she destroyed just about every relationship she had before she died. It was a very sad and lonely end... I wish she'd have gotten help.