I currently am alone by choice due to how costly girlfriends are. Time wise, they can take up a huge portion of you day and I can't have that, I need money. Money-wise, they can forget you up pretty quickly if you aren't careful. I'm sure I'll be assed enough to get another girlfriend soon or later, but in the mean time, that is my stance on them.
Or maybe if someone actually loves you they would understand why you can't be with them for that long, maybe if you got some sleep and didn't act like having a gf is just more work for you, rather than someone you want to be with, people would generally find you more attractive.
What girl wants to be with someone that treats them like they are a job?
But that's just my thoughts on the matter. :)
On a side note; people think I'm silly for thinking relationships at my age are silly (even though I'm sure soon they will start getting more serious)