I wonder if it’s reactive. She held it together well when he had the cancer and she’s just now flaking out now that things are okay and she dosn’t need to keep it together, so she goes a little nutzoid while unwinding. Happens.
Also happens that family and friends help out in a crisis, such as his cancer, if the spouse becomes unglued at some point. Then the focus goes to her after his crisis is not the A-1 priority.
It crossed my mind that the latter scenario may have been in play. But we're just speculating on all of this.