I don't understand how it has been so easy for W to put behind our M, the 10 years of memories and shared value we have.
So Pack first you don't really know if this is easy for her or not she is never going to show you her true feelings. Second she has been probably detaching from you and the marriage for years and you just were not aware.
Yes! When I was a WAH, it may have seemed sudden to my wife, but I'd been giving the relationship time for 18mo before I finally stepped away. Your grief and hers are likely just on different timelines.
