I don’t believe the young couple in the movie fell in "love at first sight". Even at the end they were not at a level that we would normally call "love". It ended before it started. But it does seem they had a wonderful time together, having fun in a very romantic way.
Some viewers said there were not much chemicals between the two. I think I know what they meant. Just as the boy in the movie said they had a connection, I think that was all they needed for a twenty-hour hour period.
It is interesting to know that people can have romantic time together (like in a dance floor with a first-met partner, or in a movie acting scene) but have not developed into a long relationship. Some people might be afraid of that, but others don’t see anything wrong if we could give each other good time more than we actually do.