Grief is a ball bouncing around in a box.
Every time it hits the wall of the box is when you feel it the most. At first, the ball barely fits inside, hitting the wall almost every moment of every day, but over time the ball starts to shrink - hitting the sides less and less frequently, but it's still inside.
Eventually, the ball will only hit the sides a few times a year, maybe less - but the ball never goes away.