I got bored
I'm hoping that this is a totally normal symptom of knitting that just does not seem to grow. Half way through sleeve two of the jumper, I got bored. I rolled it away with sleeve one and the front, tucked it into my knitting bag and conveniently forgot about it for over two months.
I rediscovered it today, after glancing at the knitting bag every so often, after being overcome with guilt. Maybe I give up on things too easily, or maybe I just go through seasons with my interests. I've knitted about an inch more now, and maybe over this long weekend the sleeve will be finished.