Am I the reason he broke up with me?

Well I think you realized your mistake. You should have let him pursue his work, its not like he was cheating on you.If you knew how important his work was to him then why try to bring him away from it?It sounds like you two deeply love eachother and yes there is still a chance that he will come back but you need to give him space to his work and time to think you. You may not realize it but you need space too...space from your thoughts on him. You also need to eventually let him know that your sorry for not supporting his work and that your willing to support it in the future if you "two" ever decide to get back together. Dont leave everything in this scenario in his hands only, remember your in the relationship too. You may feel depressed for a while, believe me I know, but you have to continue on with your life until you feel you can either move on or you two are ready to be together again.