Maybe it’s because the negativity bias operates our lives, and our brains are fixated on bad things. Example: the existence of pretty, “sexually liberated” girls who might be interested in you provided that you were still single…
On another note, I do notice this behavior as my friends are getting married and having kids one after another. “Wow, look x! What a great husband and dad he has become.” *looks of envy* I can tell they are surprised, and kind of feeling dumb because they weren’t the ones who found the treasure chest. In reality, nobody knows what kind of a man he’s behind closed doors, except his wife. Maybe he’s a douchebag but his wife is gaslighted and cosplaying as a spoiled wife.
And then, there are broken people who take pleasure from ruining relationships.