Wait, since when was she actually in love with the prince? To do point of warning him to be honest or she will answer someone else's feelings?
thinking how to explain it
Their romance is subtle, and both of them never show it on their face. Especially since we never really see Scarlet inner monolouge.
But Scarlet is also interested with the first prince ever since their first meeting. I interpet it as liking his feature. She does like pretty things.
While the prince like her eccentricity.
You can say they're interested with each other.
But well, yknow the engagement shenanigans and what not. Kinda unimportant, but they also aren't doing anything with their attraction and it's fizzle out.
Until the punching ball happens and things changed. And all about the prince feeling. Scarlet isn't that dense, she know about the Prince interest and whenever the Prince help her (like give blessing, give her chance to punch, etc), you can usually see panel of Scarlet by herself, and while I know it's not like she smile and all, that panel mean to show Scarlet appreciate the prince's help.
Scarler eventually return the prince's feeling (with her condescending to the Prince will and let him tease her a bit), but since none of them said it outloud, they didn't confirm anything.
Scarlet doesn't like beating around the bush, and it's not like she really, really attached to the Prince. She give him chance to truly pursue her, but she won't wait either.
Which is where this chapter goes.
For prince Alphaim, I don't feel Scarlet like him or will accept him. But she want to say to the prince that if he keep beating around the bush, even Alphaim is better than him.
Sorry if it's confusing. Both the MC and ML have stone face so it's kinda hard if you aren't used to their character arctype...!
TLDR, you can see Scarlet feeling by her trusting the Prince more than the others character in the series!