When you're growing up with your siblings, you think that they will always be there for you and at all the family gatherings. When you get married, you have so many plans for your future together---a house, children, grandchildren, travel. When your child is born, you have so many hopes, dreams and expectations for them. But with the death of a spouse, sibling, or child, it's not the way it's supposed to be! You expect to grow old with your spouse. You expect your child to outlive you. You expect your sibling to be around to help take care of aging parents. So their death, and its ensuing grief, are so very upsetting. With the death of parents, grandparents, aunts and uncles, you may be able to reconcile it as the natural order of life. They've lived a long and full life. But with the death of a child, sibling or spouse, it feels like they were robbed or cheated by life. That's not the natural order. It feels so wrong. And it also feels like you were robbed or cheated by the loss of their life.
I think the death of a loved one also makes it hard to trust life. Life isn't as it should be any more. It doesn't always follow a natural order. And it makes you think, "If this can happen outside of the norm, what else is going to happen?" What CAN I count on? It's very unsettling to think that you can't count on things anymore.
With the loss of the loved one's life, the expectations die as well. You begin to think in terms of "they will never get to..." get married, they will never get to have children, travel, buy a house, see their grandchildren. You won't get to experience their joy and satisfaction when achieving such accomplishments.
So where does one go with all the dashed expectations? My suggestion would be to work at making new expectations for yourself. It is not an easy process. It takes a long time to revise your expectations and resume your life after a significant loss. Try to find new social activities, hobbies, sports. Take a cruise and travel to see new sights. Recognize that you will continue to experience grief, grief bursts and periods of sadness. maybe even journal about your experiences. Attempt to learn to do some of the chores that your spouse did. Work at engaging with family and friends so that you don't withdraw too much. And if you are inclined, explore your faith/spirituality to examine how the death fits in with your prior beliefs. Seek counseling. And most of all, I hope that you will learn to trust life again and that it will restore a balance of good and difficult circumstances.