Whether it's romantic or not, Ash and Latias's interactions are heartmeltingly adorable.
More like Crowning Moment of Cute. After Ash and Latias start playing with each other, Latios flies over to Pikachu. Pikachu shrinks away from him, then as Latios starts moving his head towards Pikachu, Pikachu shuts his eyes. It turns out that Latios just licks his face to make up for attacking him earlier.
While it's never clarified whether it was Bianca or Latias-disguised-as-Bianca, Ash does receive one of very few kisses he has received over the series in this movie.