There is a gradual decrease in any kind of excitement or joy in life. Why does it seem like everybody is selfish?
From your statement it seems like you are generalizing things. Sometimes we view our surroundings in a negative light that affects our relationships. Socializing and maintaining relationships is very important for our emotional well being and for any relationship to work one needs to see both the perspectives. Lack of meaningful relationships can cause feelings of sadness. A slight modification in thought process and a little work in interpersonal relationships can help in your situation.