FY, Those who run are the ones that have unresolved issues from their childhood. The one main issue that drives the crisis is depression. Depression is about the past and anxiety is about the future.
Yes, the feeling of being unfulfilled, searching for something more and time running out is all part of the crisis. The feeling of unfulfilled for the runaways is very extreme and that's why they are out there searching for something more. Mortality plays a role as well because they do feel like they are smothered or choking and want to do everything they can before they die.
FY, years were not wasted in your marriage. What is happening to your wife right now isn't about the fulfillment in your marriage. It's about her and the feelings that she has stuffed for years and years prior to meeting you and yes, she will project those feelings/thoughts, etc. on to you because you are the most readily availble to lash out at and blame for her unhappiness. It's not YOU or your marriage!
I want to ask you something and think about it long and hard...what transpired in the 18-24 months prior to her going into crisis? Something had to have triggered her full blown mlc. Up to the point of the trigger, she may have been moving along, but there was a gnawing feeling of discontent that she hadn't felt comfortable w/discussing w/you because she wasn't sure how you would react. Then again, mlcers assume that we know how they feel and recognize their unhappiness...unless they discuss it w/us, we don't know.
Give her time and space. Contact her only when necessary...allow her to come to you.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.