Since I do not know all the circumstances with the marriage, I will tread carefully.
There are times when even the most godly person can question the reality of God, the truth of what he professes, even the point of going on another day. These times for myself have been times of great crying out, and clinging to the Lord.
I have had some very dark dark times, and if it were left to my own strength I would have failed, and simply taken my hand fromt he plow. But there is Another who lives in me, and I hope the same for this man, who drives me to continue in Him.
This young? man should work to reconcile his walk first and foremost, as this is the fountainhead from which all streams in our life flow. Though he may show up at church, and look good, something is wrong inside. This is where we must be careful not to jump to conclusions about what it is, or is not. Of course we know that God would want the marriage reconciled, and that should come a close second to the other.
May I suggest you see if there are men who are spiritual who can speak with this brother gently, and befriend him so he could share his burdens with them. Having a friend is an amazing blessing in this life we sojourn through.