Hello and Welcome to JustAnswer. Your question is not closed until you are satisfied. I am happy to assist you with your question.
As you have already learned she is closed off to discussion about this. I don't know what is wrong, but something is very wrong here. If she won't go to a therapist, please go by yourself and try to figure out what happened. You may also be able to work on some strategies which may make sexual activity appealing to her.
It wouldn't hurt for her to have a complete check up by a gynecologist, to make sure there are no medical issues, but if she won't talk about it, you really don't have a great deal of leverage.
Your best bet is to talk to a therapist experienced in sexual dysfunction and see what you can do. My best to you.