Post natal depression after both kids, coupled with the tiredness due to having kids casued her to lose her libido. The depression continued and her sex drive kept dropping until she naturally began to think that I was the reason for her feeling like this. This manifested in the EA, and her crackpot behaviour when we split. I blame the post natal depression for her being able to leave the kids with me so easily, see.
After moving out, she realised that I wasn't the problem here, which is why she made the moves to come back so quickly, and why the EA was so short lived.
However... I think the depression is still lingering, and she has self esteem/body image issues. No idea why - she really is beautiful, tall, slim, great hair. One flag I noticed recently was that just before we went off camping a couple weeks ago, she needed to buy a new swimsuit. She told me that she'd never, ever wear a bikini again because of the way she looks, and the swimsuit she almost bought (before I actually had to stop her) was the size of a freaking 8-person tent - which she believed would be the right size.
And no matter what I say to contradict what she thinks, she just laughs it off.
Jeez.
But these are only my theories. And I know there's nothing much I can do about it. Just sayin'...