If she's been with men who have certain qualities she's never experienced, it could be money, wisdom, very good taste, sex, etc. she's never satisfied with any man who has less than that. I have several exes who are pushing 30 or older and refuse to get married or settle down because they're still holding it for my equal. They're always tweeting about refusing to settle and listing their requirements which all happen to describe me. Like
@LadyJ2 said, they'd rather be with that nikka once in a while than be taken off the market by a man they deem as below them.