Keith is such a good guy, if he let the event happen and that girl convinced Aqua to choose her instead somehow then Tiara probably would have gone with him if he decided to step in and take her away.
I do kind of feel like that scene was unacceptable. It's Tiara's special day are we really gonna go over and acknowledge the girl crying? During the wedding in front of everyone? Really rude, someone should have taken her out if she was crying so dang loud both the bride and groom noticed.
At least she didn't interrupt their vows and run out crying when Aqua rejects her. Then the fairies would flood the place and how would that look in the history books. The city drowned in her tears because she was upset the prince didn't run away with her on his wedding bday.