Boundaries and limits define how you take charge of your time and space and get in touch with your feelings. They express the extent of your responsibilities and power and show others what you are willing to do or accept. 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.