If it is a serious long standing problem, get professional help to deal with this issue. The ability to be happy and enjoy other people's successes and seeing them in the spotlight shows we are secure and not envious nor jealous of others. Again, having a group, even if small, of support people and friends is vital to a life that's full and complete. Other people give us love, companionship, laughter, a sense of connection to the Universe, and other good things. Being social and sociable is a sign that you are enjoying life, and it is healthy for everyone.
Studies show that married people live longer than single people on average.
There is nothing wrong with being single at all if that is your situation or your choice. The important thing is that whatever relationships you are in, especially the intimate, close types, that you feel good about your part in them, and you are not wrestling with any severe problems or concerns that remain unresolved or unacknowledged. Attractive here means fun to be with, a good friend, kind, etc., and is not referring to physical appearance. Being friendly to people is simply that. You don't have to be friends with a stranger to say hello or excuse me or to open the door for them going into a store.