I think she was pushed into a depression. Long story short. Not too long ago my father killed my mother (medication side effects caused dementia). He went to jail where he died four months later from complications of Myasthenia gravis. She was very close to my parents. She was also interested in getting a Master's Degree, but she didn't get good enough scores on the GRE. The Master's Degree idea has been in her mind for quite some time, but one day she just decided she was going to go for it right that second so she only studied for a week. When she told me about her failing scores I hugged her and reassured her that she was smart enough to get a Master's Degree, but that most people that take the GRE study for month's upon month's. That didn't help.
There were some other things that happened too... but she has been depressed since January of 2011. Prior to that she was completely different.
I read your post yesterday and I felt as though I had written it myself, except that my husband ended things with the OW long ago but still moved out in January. Same weird behavior, same questioning everything. Also says he loves me but can't explain what he feels. How are things going for you? I hope you and your wife have made some progress.
The short answer is they don't "snap" out of it. They gradually emerge from the thick and poisonous fog which has enveloped them - and it can take many, many months from the time the affair ends.
Me: 46 W: 46 T: 23 M: 20 DS12 DD11 DS5
W left: 01/28/08 Discovered OM: 02/26/08 W back for 9 days: 04/08 W returned 05/21/08 EA/PA - 01/08-07/09 W's MLC 2008-2014 (realised this much later)
