Do you need a reason to love someone?
I get 'Fated Mates' is heavily leaning on 'love at first sight' in a fantasy setting, but even taking out the magic behind it, I get being captivated by someone's appearance at first meeting (a crush, if you will), but I just don't find that to be love until you really get to know the person.
So if I had to answer the question, yes, I genuinely think you
do need a reason to love someone romantically. Fortunately, the emperor's Fated Mate has
many reasons for her to be loved.
The bitch, on the other hand, is just piling more and more reasons to
not be loved, at least on the same level as the fairy princess, to put it mildly.