Leia was in complete denial at this point. She just could not accept it. Dealing with Luke’s trauma was a welcome distraction.

A new-EU comic series goes into how, even after the Battle of Yavin, she refuses to deal with the loss of Alderaan and has to be taken off active duty. She goes on a bit of a walkabout with Evaan Verlaine (the only Y-wing pilot to survive the Death Star) and also a survivor of Alderaan. Neat story.