My FF ate my aptasia took him a while but he did it he hasn't touch anything else that I know of and there is a lot I wish he would eat

I think filefish mostly eat/nip sps corals not so much softies/lps. Probably eat shrimp too but I don't have any shrimp so I'm not worried about that.

Sorry you lost her.
As for the reason, Copper banded Butterfly like achilles and powder blue tangs and several other fish up and die for no apparent reason.
Be grateful that you were lucky to have her with you and enjoy her for as long as you did.

How long do they live?? because if you got it as adult it might have been already old and if you have it for 4 years, it might just have died from old age?

Happens.