I've been alone and had roommates. It all depends upon the roommate, the rules and the communication.
One roommate I had was a total disaster. Thought of cleaning or picking up as "woman's work", felt free to use the stereo, my music, my games, my computer etc as he felt fit. Never caught on when I had a "special friend over" that he should give some privacy. I would find my vcr had been reprogrammed to tape something he wanted, etc. This obviously did not work out.
On the other hand, I've had some great roommates. A buddy from university came to stay on the couch for "just a week or two" until he found a new place when he and his wife split. He ended up staying 7 years until he got engaged again. There was always beer in the fridge, and he brought his own TV for his room. For almost 5 years we walked to a local pup for dinner and beers once a week and talked about any annoyances or problems that had cropped up over the past week and gave a heads up about anything that might be happen the next week. We got a second fridge and each of us had a cupboard that was "owned", no raiding that cupboard by the other. Everything else was shared. Great system and it worked well.
I have been on my own for 4 or 5 years and recently offered the bedroom to someone that needed a "temporary" place. She is working out surprisingly well, and her boyfriend leaves money on the kitchen table for groceries every couple of weeks. Neither of them drink, so that is not an issue. She stays in her "cage" more than she uses the living room. My only real annoyance is that she does not knock before coming into my bedroom to ask me something. One of these days I'm damn sure I will be embarrassed.
On a general note, it is not a good idea to have sex with a roommate. Once you do, you could be found to be in a common law relationship and things could get nasty.
Having a roommate is not just for poor people, it is also for company. I sure as shit don't want to be found 2/3rds eaten by the cats after I have not been seen for 3 months!
