From the bottom of her heart... I hope there's still heart left and she hasn't killed it all. Maybe there is, since she's still a child. No matter how much she's burdened by her no blessing status and tries to act submissive, she's still a child. She's also nobility, so it's not like she would have grown up malnourished or anything. If Shizuru convinces her that he only likes girls who have their own will, not dolls, she ought to recover quickly enough.
I also wonder if Lucina having no blessing is actually a good thing. At least in that case, their children won't get her blessing and skip Shizuru's. If lightning is all the children could receive, then it's more likely lightning. If history had proven that the children of a mother without a blessing will never receive a blessing, then it'd be unlikely Shizuru's parents would have ever accepted this marriage.