The unhappy person resents it when you try to cheer him up, because that means he has to stop dwelling on himself and start paying attention to the universe. Unhappiness is the ultimate form of self-indulgence. When you’re unhappy, you get to pay a lot of attention to yourself. You get to take yourself oh so very seriously.
The real existence of an enemy upon whom one can foist off everything evil is an enormous relief to one's conscience. You can then at least say, without hesitation, who the devil is; you are quite certain that the cause of your misfortune is outside, and not in your own attitude.
You can change the place you live, your clothes, your interests, your friends, your religion and even your partner. However, if you forgot to change your mind, attitude, beliefs about the world, how you treat people and how you plan to be different this time around, why did you even bother?
When you're young, you always think you'll meet all sorts of wonderful people, that drifting apart and losing friends is natural. You don't worry, at first, about the friends you leave behind. But as you get older, it gets harder to build friendships. Too many defenses, too little opportunity. You get busy. And by the time you realize that you've lost the dearest best friend you've ever had, years have gone by and you're mature enough to be embarrassed by your attitude and, frankly, by your arrogance.