One woman short of being gay is a term that closeted gay male husbands say to their straight wives so they can stay in a marriage of convenience.
Or sometimes the straight wives will tell this to everyone else about their marriage to deny that they are married to a closeted gay man who wants nothing but a marriage of convenience for appearance sake to appear "straight".
Belle is married to Bill and Bill is a closeted gay man, Belle likes to tell everyone that Bill is one woman short of being gay because he's in a marriage of convenience with him.
Someone who jumps from one relationship immediately into another one.
Serial monogamists can not stand to be alone and often suffer from vast commitment and insecurity issues.
Because they jump into relationships immediately after the previous one has ended, serial monogamists typically don't take the time to reflect on their behavior or why their previous relationships failed; thus, they end up making the same relationship mistakes over and over again.
Person 1: Damn, Dustin already has a new girlfriend?! It's only been two weeks since he broke up with his fiance! I think he's a sociopath.