How can I help?

I posted this in another group and was told it had no place other than here. So I’ll as you ladies.

I have a long time friend who’s been struggling with his faith. We dated in the past but later became friends after separating. Recently he and I have started doing Bible studies to try and help him grow closer to God. I’ve noticed in our last couple of studies that he seems down in a sense. It’s none of my business but he brought up he’s been having trouble with being open about his faith. He struggles with it at home. His wife gets upset with him if he tries to discuss things with her so he doesn’t. That he compromises and tries to change who he is so he can be the person she wants. He says she knows of God but is not of God. He opened up to me and said that honestly I’m the only person he can talk about his faith with. That God always brings me around him when he needs encouragement. That I have been “a true gift” to him, the “biggest blessing” since his kids were born. I have been very taken aback by this. I’ve always thought that spouses are the ones we should be able to be the most vulnerable with. As faith is a vulnerable thing, it must be so lonely to not be able to share it. To seek out someone to share it with. How can I encourage him that he can have a long, healthy marriage if his wife refuses to share the same beliefs as him?