I think he's using God as an excuse to not tell you plainly that he is the one who wants to leave the relationship. If God didn't want the relationship there would have to be something sinful about it (like fornication), not saying there is, it's just an example.
Many people are even married, and balance work, God, and their relationship just fine. I would not get back together with him because his heart is not in it, he'll keep making excuses, and a marriage with someone whose heart isn't all in it is doomed from the start. I'm sorry for your hurt. Maybe God wanted it to end because He has someone else in mind for you.