I have no idea why it's better being single. All my friends tell me that being in a relationship is much better than being single. Why is that? I definitely don't want to be alone, and I want to be in a relationship. I hate the notion of loneliness, and it often gets me depressed.
I would argue that it can be good either way. When you are single you have many options available to you to grow and mature on a personal level.
When you are in a relationship, a caring mature relationship, you have the opportunity to grow as an individual as well as grow as a couple, which can be fantastic. The flip side is that you are now part of a team, what you do, say, and feel has an effect on the other person.
It's not that one is "better" than the other, they both have their strengths and weaknesses. Don't concentrate on being lonely, instead use it as an opportunity to grow as a person.
If you can't be happy by yourself then you probably won't be happy with someone else. Too many people rely on others for their happiness. Be happy by yourself and you will attract someone then you can be happy together.
That's the theory anyway. I don't think its better to be in a relationship, at least not for me. I hate the drama and stress. I prefer being single and doing what I want when I want and having no one else to worry about!