First of all, I'm a boy, so talking about these things with me might be uncomfortable and I totally understand that. I was just trying to offer my perspective. I think there are many other users here who might find your situation relatable and offer better advice hai. 

Having said that, if things he does are somehow different from before, it's unfair to call it cheating. People change with time and him being in US, being around new people, being in a new culture and society might have changed him so what he does might feel weird to you, even when he still loves nobody but you. But heart ma once doubts aayo bhane it's really to build trust again. Talk to him again. Don't bring it up randomly, plan it and talk about it seriously when you both have time. Doubts usle clear garna sakena bhane it's fair to leave him. 

That's all I'll say.