I have heard of this story a few times... my impression has always been that this woman left on her own accord. She had cheated on her husband before, communicated with multiple men at the same time. Not to mention that everything was even more difficult given that she had psychological issues. I do believe that her family knew the extent of her issues they just wanted to undermine it for so long because they love the facade of their own "good, happy family". I have seen several interviews with her mom and sister... and I couldn't help but think that there understanding, critical thinking and knowing is so skin deep that they seemed to even deny the possibility that she might have left on her own accord. I do understand that is excruciating for a family that their loved one has abandoned them with nothing to say.... but people do arrive at places of real misery, unaddressed psychological, marital and other problems... perhaps Tammy felt stuck... married very young, 37 with three children... and she is still young. Amidst her depression, she probably feels stuck in her life maybe realizing that her family and her lifestyle were very different from what she truly wants.
Now, wrap this up with depression, self-esteem issues and stress.. this may potentially become a very significant problem. Doesn't seem like she was very responsive or receptive when her husband reached out to her to find out what's going on with her. She may have already considered going away and didn't want to further invest in her marriage.
That day, when her husband picked her up from work and then left her at home to take the kids to run errands... she may have seen that as a good opportunity to go away for good. I do think that there was definitely a third person, perhaps a man who had become Tammy's lover. She called the guy to come pick her up and they just took off...
To me, this was the only plausible thing... because...
--she was possibly seen on a motorcycle by her own daughter
--had a country house -- she couldn't go very far on foot
--she had had affairs in the past
--her actions didn't show that she was working on her marriage , and hadn't for a while (as admitted by her husband)
like I mentioned above, I think Tammy's family knows that she left on her own accord and just don't want to seriously consider that fact because it would forever break their image of ''good daughter/wife', and "good happy home". They would have to reconsider if they ever knew Tammy at all.