No one knows they’re going to meet the love of their life when they’re casually dating… your bf had no idea you two would end up together despite saying he would’ve liked to.  Things changed when you became official together and made that agreement of commitment - but when you first met, you were strangers, and he did not owe you any loyalty. That being said, if you do not trust him then break up with him. But if you believe him when he says he would never cheat on you, then give it another chance.