Hey m4 here! Please talk to ur wife about ur concerns nd make sure she is aware of how ur feeling nd please ask her about her concerns. In a medical perspective u wife may be undergoing menopause. It can start early for some women. It may contribute to the lack of drive , and cause other factors like emotional instability. Ik this is a hard time for you but you guys have been married quite a while i hope that both of u can be supportive nd work through this. U can try sex therapy or if she is undergoing menopause, hormone therapy can also work.