Acceleration is change in speed, so it is, by its very nature, relative just like speed is.
If I fall, I might accelerate at G meters per second, relative to the earth, but I don't absolutely accelerate. If the earth decelerates at the same time, I'm now both accelerating an decelerating. It's relative.
If I fall, I might accelerate at G meters per second, relative to the earth, but I don't absolutely accelerate. If the earth decelerates at the same time, I'm now both accelerating an decelerating. It's relative.