Going crazy after she died isn't proof, though any more than staying sane after someone you love dies is proof that you didn't really love that person.
Excellent point. If people were prone to insanity after death of loved ones, we'd all be in a great deal of trouble, or if real
love caused insanity when lost, and anything else was just...what, habit? That wouldn't make much sense from a survival standpoint. Dysfunction or functionality, or instability and stability aren't measures of love and can operate quite independently of pretty much any emotion.