It's not that she likes him, I think she considered him as a real brother and that he was really affectionate to her compared to others. She thought "At least, this person likes me as much as the princess" considering that everyone likes the princess more than her. She thought that at least, someone was still here to give her love.
But now even her childhood friend and heart "brother" told her he loved the princess more than her.
Eventhough she is so lovely, no one is treating her well and show her a deep feelings that she is alone. So it's not about love here. She will just feel that life is horrible to her, no one likes her and she is just alone.
The only one who loves her more than the princess is Ezekiel's father but he doesn't even give her the affection to make her feel loved.
And her "father" is literally trying to make her realize how lonely she is. Rather than aggraving the situation, he should just give her the affection she doesn't have.
I swear if it’s lack of love make Jeanette be the antagonist...or her father finally pulling her to his side. I liked her charac very much because she is kind and sweet. Jealousy is a disease, and now that the guy she likes, likes the princess, I don’t think she will stay pure-hearted.
...which I hope not.