Alaska Airlines and AeroMexico are ending their frequent flier partnership effective December 31, 2017.
This should not come as a surprise because AeroMexico is now partly owned by Delta that was also previously partner with Alaska.
You can access Alaska’s page for AeroMexico here.
Here’s the announcement that Alaska has made:
Those Mileage Plan members that had booked their AeroMexico ticket before this announcement was made can credit the ticket to the program past the December 31, 2017, cut off date.
More partners is always better but I would assume that Delta was behind this move.