> The other possibility is that you are a paranoid maniac.

Lol. The false dichotomy and palpable angst is strong here.

How about they may have a undiagnosed mental disorder, and should seek professional treatment to discover how others deal with this?

Anecdotally, children who had parents that cheated on each other and had terrible divorces are more likely to have trust issues because they think the other shoe will drop any moment.

Rather than lashing out at folks reading your post who might have had a terrible childhood, maybe be understanding and suggest that the behavior is abnormal and detrimental to their goal of having a happy life.