Yes, it does become a far too frequent occurrence as we age. My mom had close friends of a wide variety of ages, but when her last childhood friend passed away, in their 90s, it hit her the hardest. She said there was no longer a single person with the same lifelong memories as her. She had outlived her immediate family when she turned 42, but it wasn't until 95 that she outlived all her friends.

You'd think you get used to it, but you don't.