Chuck, your W sounds like she is taking Amphetamine. That will certainly drop the weight and keep a person from eating. Does she have trouble sleeping? If she is taking other prescriptions or drinking....it could be fatal.
The other things sound pretty much like she's in an EA. Just b/c OM denied it....and has a GF....doesn't mean your W isn't head over hills for him. If there is a rumor, then obviously others have noticed "something" in their behavior.
Have you decided if you are done with the M?
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!