Sometimes, there might be deeper reasons when interests seemed to die down. For women, it can be rooted from stresses, expectations of herself, her inner challenges. It may be difficult for her to share out what she really wants also becoz she may be confused herself. You might consider talking...
From experience, it can be really tough. Besides communicating with each other, Counselling can help each other to move on, whether in marriage or outside. If you need recommendations, i can recommend marriage counsellor to you.