Long distance

My fiancé have been together for 3 years now. We started dating online and he moved to my country for a year and relocated to another country again (we’re from the same country). Things have been very rough for us. From infidelities and all. He moved in October last year and things were great when we started till i got a new job that is very demanding and the time difference between us is 6 hours so we don’t really get time to talk but we try. Lately things with him has been off, i feel so disconnected from him and he’s been really depressed so affection from his side has been very withdrawn. I’m really scared cos idk how to help him. What do i do?