MLC can happen to anyone, i.e., married, single, and doesn't single out couples by the years that they have been married.
Sounds like PPD kicked in and she feels trapped being home all of the time. She misses the attention of working and the business trips, i.e., the excitement of doing something w/her life. Now, she thinks her life is boring w/no purpose except being home and raising children.
I suggest that you stop writing cards, offering trips or dinners, as well as times away. She feels pressure and it sure looks like pursuit on your part. Just leave her be. She can't work on herself if you are there front and center. Her focus is on you and it now needs to be on herself.
I would not get involved w/someone else until you are, heavens forbid, divorced. Why? What would happen if she work up and wanted to work on things w/you? There would then be three in the relationship and someone would get hurt. Do not give her anything in the way of justification as to why she's doing this stuff. If she were to see you getting involved w/someone else or just dating, that would give her justification to do the same thing or bring it up in a divorce proceeding. You are smart to leave this be until you are absolutely certain the marriage is over, filed and done with.
Dig deeper for patience and when in doubt about something, do nothing. If you sit quietly, the answers will be revealed to you when you least expect them.
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.
