I know Satoru and Airi didn't get together in the anime. Do they get together in the manga?
As this answer discusses, in the manga Airi shows up a few times while Satoru is recovering after his coma, although they never really directly interact. While the ending of the manga is quite different to that of the anime, the very last scene is the same:
Satoru goes back to the spot under the bridge where he hid from the police, and as he hoped Airi shows up there as well.
Based on the anime and the manga, the last scene is Satoru going under the bridge where he hid with Airi after he was accused of murdering his mother. There he used his hands to form a rectangle, and as he saw through the rectangle, he saw Airi.
There is no continuation of this story, but considering that Hinazuki Kayo ends up with one of their friends (Sugita Hiromi) and is living happily, it is implied that Satoru seeing Airi there means that his own love story will finally start (with Airi). It wasn't explicitly mentioned, so I believe it was intended to be left open to fans interpretation.
In this case, it remains to be seen. Airi does stand up for Satoru several times, but they never really are seen engaing in any actions that would quite sum up to a 'romance', more of a relationship built using mutual trust and help.