Have you tried counseling yet?
If he won't go for that then it is time to let go. Christian counseling is the best if he will do this, if he really loves you.
Father, I lift up this couple to you and ask that you would help them to work things out and would heal the hurts. Father, God, you are the only one who knows for sure what is going on and how to fix this. Lord, Open their hearts and spirits to your leading, and heal this marriage, Father, in every way. Strengthen their love for each other, grant them the willingnes to follow your will Lord, what ever that may be, and where ever that may take them. Lord, I ask that you would bless them and their relationship as they work to come back together again. Fathr, bring them not onnly closer to each other but also closer to you, for only in you is the healing they need. Father I thank you for the answer to this and all prayers for this couple, and for the blessinngs to follow. Thank You Father, In Jesus name
My prayers will be with you, May God bless you