LOL, it was opposite when I got here. People were going off about Pearl, but no one said anything about Kira (it's probably my fault, I started bitching about it, Hahaha).
Why I see it as worse, and this is just my opinion, I know others will see it differently.
For me, Kira made a deal with the Adventurer's guild with the intention of seeing what her and her father could get out of it. She took MC to him for her own greed and doesn't apologize for her betrayal, MC says he feels betrayed, but within seconds is over it and forgives her cause he's drooling over her.
For Pearl, she didn't actually betray anyone, because she made no deal with the MC or the Guild. She was also blackmailed into doing it at risk of her sister's life. Sure, she could have done things differently, but she was torn and trying to protect her sister. She was also extremely apologetic to MC and remorseful for not doing things differently.