She is someone who is new, fresh and probably exciting. Someone who has not been caught up in his drama over the last 3 years, (the grief his ex (his S's Mum) caused him), she would not have been involved in any of this or saw the effect his ex had on him. She doesn't remind him of his past.
The newnest truly has an impact. It is exciting, think about it honey, remember when you first fell in love. Your h seems to be addicted to that "feeling". He obviously loves being in "love" but hates the pain when it stops. Your h has not figured out the difference between "true love" and "infatuation/twitterpation". Look it up SpecialK... it is quite fascinating.
It appears your h has had several OP's. Tell me, how long did each relationship last? Research will often provide some answers. Now, why they are the way they are... good golly, that is anybodies guess.
They just are!
I think when a lot of time is spent trying to find out answers to why your spouse is doing what they are, I believe is a "distraction" technique we use to avoid "facing" our own demons. We have been given a gift of time, as OP tells each and every one of us, as we join this forum. He is absolutely correct. It is a precious gift, which we are squandering when we WASTE precious moments trying to figure out what is going on in an MLCer's mind.
Quite honestly, whatever an MLCer is thinking, is like the weather here in Luxembourg, wait 5 minutes and it will CHANGE!!!!! They are very, very confused people SpecialK. Use this gift of time for yourself dear... and let your husband "twist in the wind"! Once you are healthy, healed and ready to move forward, you can bring him in to dry, until then, leave him to it!
hugs Stayed