Another thought I had on why Amy would go with him. If Amy and Tonya had been talking recently about the growing relationship issues and add in Beebe's violent past, she would have feared for her friend being alone with him. I personally have had a friend with a violent boyfriend and my response was to want to help her and keep her safe. In my talks with her, I assured her that she wasn't alone, and I would be there for her if she needed to get away. I even went with this friend (I have a permit to carry) to retrieve belongings. I think that if Amy would have thought that a fight was going to break out between the two of them, I can totally reason with why she would go along. I would justify it by thinking most domestic violence would stay between the people who had so much anger towards each other. It wouldn't make sense that the abusive boyfriend would come after me, so I don't think I would fear for my own safety as much in that sort of situation. Sounds a little silly in retrospect, but it made sense to me at the time. As close as their families were, she has known this guy for 12+ years and I doubt she would have ever believed he would harm her knowing what her familly would do if they found out. I just don't see how she could have ever expected this outcome, and my guess is still whatever happened when the fight got out of hand, she was most certainly not expecting it.
I am leaning more towards Amy knowing her husband would come home during lunch and see she wasn't there and start looking for her. She knew her boys would be OK, because her husband would know she wasn't home. I don't think she was in a huge hurry to get out of there until she felt Tonya would be safe. I can see a 12 hour argument going on and Amy still thinking, my family will know to find me here and any minute they will walk through that door (which is the biggest part that still baffles me, why didn't anyone look for her there) and as more and more time went on, Beebe got more and more angry about the domestic argument that started it all to begin with. I can also see that if Amy had been talking to James about the issues between Tonya and Beebe, James could have thought that Amy went with Tonya somewhere safe to get her away and that she would still be walking through that door as soon as Tonya was safe. When 10:00 rolls around and they call Beebe and make the mistake of telling him someone witnessed him at the Henslee house... Beebe realizes police are now involved and starts thinking irrationally and possibly planning his escape. If there was any sort of -- you are in for it now Mr. girlfriend beater, they are going to lock you up forever thing going on, that would have also fueled the irrational thinking. If there were drugs or alcohol involved, that could have fueled the feeling that the only way out of this was to kill them both.
I have no actual basis for this theory, just trying to come up with the story that makes the most sense to me also. Except for the lack of searching this guys property, I don't think a premeditated killing makes fits.
One more thing, I was also able to look at Beebe's son's facebook pages before they hid his friends from the public. One of the sons had about 20 friends on his friends list and a good bit of them were the Henslee family most of whom had changed their profiles to Amy's picture. We know Beebe was on facebook because he had added pictures, so surely he must have seen the fact that his son is now looking at picture after picture of Amy missing, and that he is the reason for that. He has to know how much that is going to hurt his son also. I would be willing to bet that Beebe's sons also loved Amy very much! There was certainly not a lot of rational thinking going on this Monday/Tuesday by him.