In my experience (without too much deep thought) there are two main areas this can help in.
Guilt. When I felt guilty I took it out on my wife. I'd get irritable and withdrawn.
Building Desire - I was always desirous, but not for my wife. For SEX. Yeah, only with her, but it was the physical, not the emotional. Don't get me wrong, I'm not sure she even knew, but I did. I'd get angry if we were not together (b'loshon more noki than above) and would cause passive aggressive fights from that. B"H, she has really noticed the difference in the time I've been here.