Comparing myself to others makes me feel bad.

Self-centeredness comes into play when there is not enough self-esteem — not the other way around… Putting others down as a way to feel better about oneself is whack and unattractive. And while [a Diva] may appear confident and strong, usually the opposite holds true.
Quotation from Curly Nikki, Tyra Show

Certain people make a habit of anger. They seethe with resentment, which is very hard for them to overcome. Some psychiatrists consider this chronic bitterness to be a mental disorder called Post-Traumatic Embitterment Disorder. The scary fact is this happens also to “normal” people who suffer an unexpected setback such as job loss, divorce, or financial shock. I wish there was a simple, green, heart-shaped pill available to cure everyone’s anger!

They feel the world has treated them unfairly. It’s one step more complex than anger. They’re angry plus helpless.
Quotation from Dr. Michael Linden, who estimates 1% to 2% of the population meets the criterion for Post-Traumatic Embitterment Disorder

Embitterment is a violation of basic beliefs. It causes a very severe emotional reaction… We are always coping with negative life events. It’s the reaction that varies.
Another quotation from Dr. Michael Linden

His issue was not that I was with somebody else, per se. What bothered him is that I was with another woman.