Personality Disorders Support Group
Personality disorders form a class of mental disorders that are characterized by long-lasting rigid patterns of thought and behaviour. Personality disorders are seen by the American Psychiatric Association as an enduring pattern of inner experience and behavior that deviates markedly from the expectations of the culture of the individual who exhibits it.

It's a horrible condition to have to deal with. I'm here if you want to commiserate.
The treatment is to have him/her learn that this is a faulty belief and that he.she can handle things. (but sometimes they don't "want to"). Unfortunately there is usually an "enabler" who steps in to care for the person, undermining their independence. Then it becomes in his/her interest to stay dependent.
First I would ask if his wife had actually been diagnosed or did he diagnose her.
Next I would state that a certain amount of avoidance, blaming, catastrophizing, dependence, depression, domestic theft, emotional blackmail, engulfment, wanting a better life-entitlement, fear of abandonment, feeling of abandonment, feeling of emptiness, harassment, inability to trust-lack of object constancy, low self esteem-low functioning, magical thinking-intuition?, mirroring, panic attacks, turning to the kids-parentification, perfectionism-wanting a faithful spouse?, projection-guessing your feelings, sabatage-provoking conflict, self loathing, self victimizing, stalking and testing could be tied in with his infidelity.
If his wife is doing the above it is not healthy for her or the ones around her, but other factors seem to have been left out of the original post.
I wish there was a way to purge outdated posts... : )