Definitely sounds like you are the type of runner who is motivated by having the team and others around you but maybe don't have the mental drive to do all the training by yourself. Like others said, try and find a group to run with on the bulk of your runs and see if that gets you going again.
I was the same way in many ways. I would always have a problem on my own getting in my second run of the day during times when I was away from my college team. I lived for racing, not so much for training (even though I did train about as hard as I could). Guessing you might be the same type.