Did your wife ever have something negative happen to her sexually. For example, was there any abuse in her life? Was there a difficult childbirth that made things painful for her?
Another issue, CONTROL.
I just read recently that many woman who are "together" and have this need to have things in total order don't like sex because they feel that during an orgasm they may lose control. They can not allow themselves to reach this point because it is something they can not control.
Another issue is vulnerability. Making ourselves vulnerable in the bedroom is hard. Allowing that part of us to be totally exposed especially after going through such a rocky period.
I am just throwing these things out there because the problem is about her not you. Something is going on in her head.
There can be no testimony without a test. I am praying to go through this test and come out the other end with a new and better marriage then before.