this is not a first break up, telling me that there were probably on going problems that you aren't mentioning here, which is your prerogative but I only point this out for this reason, maybe this is the time to move on and let him go?

I cannot say whether or not he needs to grow up and/or mature, because I'm only seeing your interpretation of the break up, the relationship and his behavior. Assuming you're right on a lot of those things I would ask you, do you really want to keep doing this with him? If a lot of this is his doing, considering the break ups, perhaps he's not ready to commit anyway and it's time for you to find someone more mature and ready for those things.

If he's found someone else he's interested in, it's kind of a sign he's moving on and away from you and your second guessing his reasons, his motivations and whether or not its a mistake for him is only going to serve to make you more angry, resentful and miserable.

based on your comments about him I'd say you can probably do better anyway! Enjoy yourself as a single for a bit and find yourself. I guarantee you'll be much happier and when someone comes along you're probably going to be in a better place to decide if you want to have a relationship with them.