I think she got sixir/evil eye on her. You need to call the culumaas asap. The guy too, one would think he would have divorced her but as you are telling something is holding him back...he also needs quraan saar. You also mentioned he is pretty wealthy and they are both religious...another reason why to think this is sixir related. Seriously, call the sheiksh of your city and see if Ruqiya Sharia and Quran helps to restore the love, joy and peacefulness in their household inshaAllah.
If it doesnt work they need to see a terapist, also have they even talked about this issue? Like what is her answere to this situation and why the heck is she refusing him to enter the kitchen?! She never prepares any meal for him? Does she only prepare for herself?, xaasidsanaa

I think the βsixirβ is in the kitchen tell the sheikhs to throw some holy water in the kitchen and bedroom and look for some fishy knotted hair or nails in the house...