Wow, 23 so young to be in a situation like that. Don't mean to be mean but he's better off without all that baggage. As for selling his stuff... Did this girl ever demand him to get rid of it? I would be concerned that he's doing it to try to get her back. If they started dating 7 years ago and he's 23 there first date was probably in that truck and he probably wants to get ride of all memories of her (fresh start). I really don't know the signs of depression, but it sounds to me that he's just trying to move on. I hope!

Good luck!