It's a really crazy thing to experience, grief is a feeling that is shared-- I think-- across animals, it's one of the deepest feelings we have that is also felt by others, not just humans. But since I can only speak for humans, here it is. I think grief is about as bittersweet as it gets. Grief is the feeling of absence; the feeling of losing a love that was once there, which is to say, there is a part of you that go to experience that love and that's something to be grateful for. I've found that grieving people who are still alive is so strange, there's always a part of me that wants to will the person back into my life but I always wonder if it's worth it. Sometimes I also grieve for my younger self. All the endless possibilities of what I could've been if the circumstances were different. It can make you spiral a bit, so I suppose a word of advice (that no one really asked for and that's okay): find ways to ground yourself, find people who help you ground yourself, and always remember that you're here and that's enough.