Disclaimer: I do not own Star Wars. If I did, the prequel trilogy would have had a different feel to it. But that's a separate story.
It isn't fair. They've lived through so much, given so much, lost so much.
The day they were born, they lost their birth parents. They've lived through the Empire, and both lost their guardians. Leia lost her world, Luke lost his mentor. They joined the Rebellion, and every lost member of the Rebellion was another loss for them. Luke lost another mentor, and she almost lost the love of her life. They both lost the birth father who almost came back, but they freed the Empire from the Emperor.
It didn't end there. They gave their all, working to make the Rebellion into a Republic. Luke pours his heart into the creation of the Jedi, and Leia pours her soul into the Republic. They both answer every call everyone makes on them. They give of themselves to a Republic and people that hardly ever give back.
Luke is the Jedi, and Leia is Chief of State. People look to them to solve things. They aren't allowed to ask for things, for family time. Leia has three kids she never watched growing up. Luke has a wife he barely sees, and a son he doesn't know. Leia and Luke are famous, and they've done so much for the galaxy, but they missed all the important things.
And after everything, a new war comes and takes even more.
The Yuzong Vong take Chewie, and Anakin, and they aren't given time to grieve. Leia for the son she barely knew, and his future that will never come, and for her husband's companion that was more a constant than she was. Luke for his nephew, a promising jedi and one of his oldest friends. They aren't given time, instead are expected to solve the problem. There is no break for them, no time to feel and grieve.
And after the war, comes a civil war that steals Mara Jade and Jacen. There is no freedom, no break. They aren't allowed to grieve for Jacen, because he turned. And Mara Jade was killed by Jacen. It isn't fair, Leia wants to cry out to the world. Why does her family have to give and sacrifice? Their father killed their mother, Luke almost killed their father and was almost killed by him, Mara Jade was killed by Jacen who was killed by Jaina. Most of the members of their direct family are killed by family. It isn't fair.
Why does their family have to give so much, with so little in return?
Why are she and Luke still alive after they've lived long and (mostly) fulfilling lives?
Why isn't it some other family's turn?
(But even as she thinks it, she knows she would never wish this fate on anyone else.)
She is her father's daughter and her mother's daughter and if she can take the pain to save billions she will.
And in the end, as she hides her granddaughter as an orphan she picked up, she realizes that it's in her name.
Skywalker. They who walk the sky. They have no home, they are wanderers. And wanderers are able to give up that which will not help them on their journeys.
Her family suffers like it does because they have no home to go back to. They have no duty to anything less than everything. Born from nothing, they carry with them all they will ever need, and know that when they die they will return to the force that has claimed them as its chess pieces.
Her family suffers because they have already lost everything and appeared to bounce back.
(what would anyone do if they had just given up?)
(but that was never an option. Not for their mother, father, brother, or her children.)
Sometimes Leia wished the world was fair and everyone who had a hardship and overcame it was given a better life.
(But what if life was fair, and they deserved everything that happened to them?)