Thoughts on people who are good at breaking up and prone to sulking

There is only one reason why someone is good at saying things like that.
It comes from a strong conviction that no matter what they do, this relationship won't end.
If they are doing it consciously, they are toxic; if they are doing it unconsciously, it is somewhat more forgivable.
I think this applies to any kind of relationship, whether it's work, friends, family, or romantic partners.