Hmmm. I guess you have seen the other speculation about her physical/mental health. I didn't want to comment on it, because it's an anonymous email to Greta Van Susteren, now "confirmed" by an anonymous poster elsewhere who allegedly knows the family.
Too much "anonymity" of the sources there. (And the email says that Mary's mother died 2 years ago, which isn't true - she died in 1999, so the whole thing is questionable to me.)
They claimed that she has lupus and has been treated in the past for bi-polar disorder. That sure seems like something people in a town as small as Selmer, population 4,600, would have heard about, especially lupus.
If either of these things were true, she may not have been able to establish a confidential resource in her new hometown for counseling and medication, if needed.
A fleeting thought was that her going to Henderson so many hours per week (however many) for college courses may have been a cover--but it is FHU and her in-laws are there and have access to records. She probably couldn't have gotten away with that.
I wonder, if true, that this could be "steroid Psychosis". One of the treatments for lupus is prednisone and it will cause Psychosis in high doses or long term use.