I'm not even sure whether there is existence of such phrasal verb in English or not. But probably native speakers can help me out with this.
All of your friend's problems are due to his recent divorce.
All of your friend's problems _____ [back/down] to his recent divorce.
Note: I guess I saw a phrasal verb with exactly this meaning but unfortunately can't remember it.
down are just two guesses for the possibly preposition part.