The news the letter carried was not the best. Edgar didn't know when he would be able to return to Erfreut. His father had deteriorated considerably and the enemy attacks were getting stronger. There was no possibility for him to leave everything and be with Delina, in order for them to marry.
Edgar was doing his best to prevent the monsters of Dorchadas Forest from advancing on the flanks. Not because he just wanted to prevent Wirksamkeit from being attacked, but because if the monsters made it past the barrier, they would attack Erfreut. And to Edgar, Delina's safety was what mattered most to him.
In the letter, he said he wished she was by his side, he would feel relieved to have her with him, all the time, knowing she was safe. But not on the battlefield. There, he would not be able to protect her and the others. He could not risk losing her. Or even hurting her.
