That was just the counterpoint. Without a crystal ball (that was infallible), we can't be sure that things will be better with our X, just like we can't be sure things would be better with someone else.
If you wanted to know my personal opinion: I'd say that if you know your spouse/ex-spouse, if they are someone whose life you want to share, you are aware of their faults and have already accepted them, they made a mistake but they worked through it, then I think you can have a BETTER marriage to your ex than looking for someone else. With someone new, it just takes some time to find new issues to deal with.
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer
