Have you developed deal-breaker habits?
I once read a study’s findings that men who were married/partnered in midlife and older lived longer than men who weren’t. The researchers explanation? That if a man has a physical ailment, he’ll let it go, not wanting to see a doctor, thinking it will clear up on it’s own. If he lives with a woman who knows about the malady, she insists (nags?) him to see the doctor. Thus, ailments that would get worse in time are nipped in the bud and healed.
As we get older, many of us develop bad habits (like thinking something will clear up on its own). If we live by ourselves, or with a non-friend or non-relative roommate, or have friends that aren’t very forthcoming to give us feedback, it’s easy to start doing things that are unacceptable to others but we think are normal.
This is why some people are in the “undateable” category, no matter how smart or nice they may be.