I mean, is it really that weird that the prince ended up liking her? To put it in a crude way, this is just just a basic case of 'Rescue romance effect'. The prince was going through a very hard time, he had a lot of bottled up emotions and then ended up getting attached to the mc who got them out of the slump.
It does move fast, but in the week she spent with him, he supposedly got to muster up the courage to get out of a very abusive environment due to her interference, and they then went through another sort of traumatic (ig) situation where they bonded even further by having to work together doing something that was described to us as dangerous.
For all we know, he hasn't even met Lucia, her cousin.
Idk, just a lil rant.
I know she is the main character but it's weird that even the person who she was supposed to make her sisters fiancee is leaning towards her more like this whole think where the main character is with all the main lead is weird