Single means you're allowed to do whatever you want, and not worry about someone to care for and such, but what do you prefer - being in a relationship, or being single?
If I honestly love the person, then I'd choose being with her over anything. If I just decide to be with someone because I'm lonely, then it gets boring quickly.
I'm in a relationship, and I'm pretty happy about it. Then again, we're not really on a chain like some people may be in relationships. My girlfriend and I talk about pretty much anything on our minds, including seeing other people or having a swing. I'm pretty much okay with her doing whatever she wants as long as she's careful about it. I'm not really the jealous type in that regard.