Neither of you committed to each other. I can relate it can be terrifying. You say he was there for you in every way, yet you believe he owed you more. The reality is he owed you nothing, committed to nothing with you bar him being extremely generous towards you. Yet somehow you interpreted this as a betrayal. Perhaps in his eyes it was easier to go back to something familiar than risk being hurt with you. As it appears you made very little effort to show him your appreciation. Relationships are all about communication, you seem to have hastily judged another without it seems any self reflection on your part.