I think there are two main reasons why grief doesn't abate. The first is self-pity. I am entitled to something. God owes me something. The world owes me something. Life owes me something, and I must have it. My life isn't the same without it, and I get spiraled down into myself as I think about my loss, sort of as a measure of what I deserve from life. Over time, this would better be called bitterness than grief.
So, having said that that's a possibility, let me speak to the broader and I think more important of the two categories, which is grief that just does not relent and it aches and I did not expect it to ache this long and it seems to still be aching and I'm not sure why. I cannot seem to get over it. I want to start by saying getting over it is maybe not the best way to capture the biblical response to grief. I remember when my father died, my younger sister, a teenager, saying that people keep telling her in time it will get better. She said, You know, I don't really want this to get better. There's a way where my missing of my dad, my loss of him, it captures the sense of how much I loved him, and the idea of getting better almost feels like I'll be more distant from him. There was something deeply right to what this teenage young woman was trying to articulate. There's a right way to say, God has given something and it's been precious to me.
In that sense, I think we see... Jesus will bear scars for eternity. Your story of redemption will take into account the griefs and sorrows you have experienced, and your ability to sing his praises and worship him forever will be deeply connected to the sufferings you've gone through. In one sense, every loss is indeed an experience of God gave something good and right and beautiful and wonderful, and life was different and deprived without it and his redemption in heaven will restore your joy in it, but you'll speak of redemption differently than simply like, oh yeah, it doesn't really bother me anymore.
There's a right way to have time heal, but there's a right way to say, I'm never going to be the same as I was before this loss. Part of enduring well is to recognize Christ bears these scars and every taste of grief is actually a taste of God's good gift in this thing I have lost. And there's a right way to go to him both for comfort and with grief and sorrow, just pouring out your heart as it continues to be your sorrow, even as the ache of this world is on his heart, and then recognizing ultimately there is a worship that comes out of an appreciation for him as a Giver of good gifts that grief underlines in this painful yet beautiful way.