Riight?? I mean I know why she did that, she wants to give Kaname the life (as a human) just like he did for her before.. but still I think it will be better for them if they just focus on the future than obsessed with Kaname after all he did for her..
And now it's the kids who have to deals with the aftermath =_="
She was content with Zero and their daughters...then Zero died so she gave up her life to revive Kaneme.
*Kaname
She left her daughters alone. I even felt that since Zero died, his use expired.
She didn't leave her daughters alone (her daughters are also like really old now) she gave her daughter her father.
I'd never understand why Yuuki couldn't be content to be with Zero and their daughters... sure, Kaname was a big part and an important loved one in her life but look at Aido, he loved Sayori so much and he respected the limits of life and death. Kaname wanted Yuuki to be happy with Zero, but in the end she was still obsessed with Kaname to the point of breaking inmortality's rules.