
It obviously is the Blonde one callisto! But here's an. Extra explained that I found on novel updates! Enjoyyy
Its one of those situations where she at first says "no" cuz she's mad at him but then one thing leads to another and eventually says "yes". She's mad because she can't say no for long when Callisto gets puppy-eyed and asks for forgiveness and pity, she can't help but forgive him.
What you have to understand that after the main story, is that Penelope has all the power in the relationship. Callisto may appear to be proud, confident, in control, but he's a mess when it comes to her. He knows she Isekai'd to their world through the mirror and is absolutely scared that she'll choose to leave one day. So right after the main story, Callisto tries to speed up their engagement/wedding so she won't think about leaving him, but Penelope is PISSED he's going full speed ahead without keeping her in the loop of HER OWN POSSIBLE WEDDING, and she never actually accepted his proposal (although it was obvious they were a couple). I think the first 1-30 side stories is about them learning to become a real couple who have arguments and work out solutions together. So we find out that Callisto is actually insecure, his #1 fear is that Penelope will leave him, he learns that no, keeping her trapped in the palace is an absolute terrible idea and a great way for Penelope to ditch him - so he stops that. Eventually they have a talk where she threatens to leave him, he's on his knees begging for forgiveness, she lays down rules and he obliges. Penelope sleeps over with Callisto often (I forget if its her bedroom or his) to help out his insomnia (because he thinks she'll run away at night)... and its implied they're very sexually active (consent implied).
So to summarize:
Penelope is actually a boss lady and Callisto listens to whatever her demands are. She actually does love him a lot and doesn't stay mad at him forever. He'll apologize and they make up after snuggling ٩(๑❛ᴗ❛๑)۶
Can someone fast forward me to the day when She, who's afraid of his aura itself can't resist his puppy eyes and can't stay mad at him for long, and sleeps over with him bcz of his insomnia... Omg i found the cutest spoiler in extras.. They're so wholesome and callisto is so scared of losing him. If anyone wants to know more pls do tell I'll write the whole spoiler ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄