How old are the kids?

does it really matter?

but i guess if you want to get into logistics your guess is probably right although i would've said thirteen for louie and eleven and half or twelve for cecilia

I think Louie is 10 and Cecilia is 8.

Because as we ALL know, OP, is that a person's age can be determined by height and size alone. /sarcasm

They're both probably ten. Louie is just old enough to start taking a notice in girls, but is still young enough to grossed out by one kissing him. Plus he's still young enough to want to "run away to the circus", a common trope amongst kids, and he's childish enough to think that his mother doting on him in public, is a good enough reason to run away. Of course Cecilia kisses him, girls tend to mature (or hit puberty) sooner than boys, so it stands to reason that she would openly show affection and make her crush known.

Not to mention Rex states at the end that they make quite the cute couple. So it's not a stretch to say they're probably boyfriend/girlfriend in the terms of childen think of them. They go on "dates", like the boat ride around Central Park, chaperoned by one or both of their parents (hence how we see photographs of the two together) and the farthest their showing affection goes would be: hand-holding, a peck on the cheek, and Louie winning Cecilia a gift at a carnival or something. It would be very innocent.

I could've sworn the movie said they were both 6, which always made me very confused because they both look and act twice that number, if not older.