Mostly cuz she's a heroine, since she ain't no re-incarnator and other stories that have same setting just make the heroine a manipulator. In this setting she's sentimental with the MC because she can sense how deeply she cares for her family. Whit the slight show of their dream conected i'd weager that the "specialty" of Tiara is Empathy, she can persive intention and feelings with people, if Pride ever sway she'd be able to tell inmediatly. It could be a great assurance and a plot revelation in a game.