I'm a Jerk

One night I was feeling lonely, so I went to my girlfriend's house. She wasn't expecting me, but I was able to calm her down. She was a bit hesitant, but I didn't think anything of it. I got her into the bed finally, and you know what happens next. In the morning, when I woke up she was still asleep. So I got up and left quietly. On the way back home I felt a little bad but I didn't know why. And then it hit me. I don't have a girlfriend.