That it's something that happens to all of us does not make it any easier to process. You still lose someone you love, sometimes very abruptly and while they could've easily lived years longer without an issue. You will never be able to speak to them, to see them in front of you, to hear their thoughts, to make new memories Witt them. Sometimes it also makes you lose a support network, a pivotal person that made your life better.
It may be normal, but he mental impact will in many cases be huge.