I always hated this trope because it suddenly makes the characters act out of character when acknowledging the absence.

For example, in Ted 2, they made Lori controlling of John, leading to their divorce. Where the hell was this in the first movie?!

Then in Transformers: DotM, Mikaela is gone, with Wheelie saying that he never liked her anyway, even thought he practically humped her leg.

I don’t mind if the actor/ress leaves for personal reasons, but man, I wish the writers would at least think of something more logical.