When are you most saddest for being single and why?

When I’m at a restaurant or a park or an event and I see couples. Especially couples holding hands.

I know I’m an emotionally immature and unstable loser, and I know that I have a past history of verbal abuse. I shouldn’t become romantically involved with anyone because it will always be parasitic at best. I still get really lonely and jealous when I see other happy people.