Hello.
As you mentioned your wife is not able to control the thoughts and deal with it, hence she tends to feel mentally fatigue due to the excessive thoughts. This could indicate OCD, with specific to Scrupulosity. This is a type of OCD where the person feels that he/she must do certain things religiously inorder to be fine or for things to go well. The thought can vary from person to person.
The person with scrupulosity may feel that if they do not do these religious practices something harm may come to them or their family. This thought induces extreme anxiety on the person and in order to reduce the anxiety the person tends to indulge in the religious practices.
Next Steps
It is very important to meet a psychiatrist and let him/her know the situation so that help can be provided and your wife may feel better.
Health Tips
It is very important to understand what is happening and support your wife as much as you can. Usually the people going through this would definitely want somebody to talk to and empathise with them. I encourage you to understand more about OCD and scrupulosity so that you can be more understanding and comfort your wife as much as you can.
It is treatable with right methods and suport.