Even though you're a princess who have a higher position than a 'knight' like Akito, you fell in love with him. This was a sad fact since any royal members shouldn't have a romantic feeling to someone who is 'lower' than them.

While he's guarding you in your room like the usual, he noticed your sad face when you were zooning out, thinking about your marriage your father talked earlier

"Are you okay, princess?" he asked with a worried tone in it.