Husband and I have been the victims of broken seat before (in Y). The flight was full in Y, but not in CW (it was pre WT+).

The crew solved the situation by upgrading another (older) couple to CW and putting us in their (functioning/safe) Y seats. An acceptable solution - if sort of frustrating (we got the broken seats, so someone else gets an upgrade...). BUT I actually see the logic in this: if passengers get the idea what "broken seat" equals upgrade, airlines may be dealing with a LOT more broken seats! (not from hubby and I, obviously, but not everyone has consciences like us...). Of course, it probably didn't help that the guy sitting next to us (window, middle, aisle) kept saying "you two will probably get upgraded now!" in a loud voice, multiple times, whilst the crew were trying to resolve the matter...

So I can see where they came from. Maybe they could have done similar for you - moved a single passenger to J in a way that allowed you and your partner to sit together...

Boo