I thought my experience may help someone.
I had a best friend time ago. I was in a bad point of my life and they were my only source of support. One day, they committed suicide and at first the pain was extremely intense. I had no one else to talk and the only reason I had to stay alive disappeared. At that time, it was one of the worst things I've felt.
Flash forward years later. I was a completely different person and was thinking on said person. Today we wouldn't be friends at all. I was too different back then, but they are the kind of person I can't stand being near them. I won't give details or ideological rants but I looked out messages and what kind of person they were, and my answer was: "how could I befriend someone like this?". There was no reason to feel I lost anything and given enough years, I wouldn't love them. We are to different. We have nothing in common. I simply grabbed whatever I had then.
And then I realized: We only miss them because we weren't over yet. If it happened before their death, our experiences would be very different. Think about this: most groups of friends lose contact over time, but when one of them dies while it lasts, the pain seems to be forever. This isn't correct since if they parted ways in life, they wouldn't miss them near as much if the relationship is over. You miss the time you spent with that person and if you naturally parted ways, you would overcome it. I've seen this happen to many people.
Maybe your relationship was truly special, there are always exceptions and some people truly seem made for each other. Some people may have lost their elders in childhood or an extremely vulnerable period. This may not be useful to everyone and to be fair, years made me super cold. I apologize if it sounds unemphatic, I tried to be as careful as I could and I didn't intend to say anything on the lines of "why to care if they are dead". It's an extremely painful experience and it's natural to feel like this, but it's also something you have to overcome eventually. I hope I could help someone with this.