In the Little wood (1995)

One summer's afternoon, Laure and Vincent decide to go for a picnic - just the two of them. But Laure's younger sister Sarah manages to join in. Their minds fuddled by wine and the afternoon heat, the two adolescents end up awkwardly expressing their fondness for each other. Sarah, whom they have both forgotten, witnesses the scene.

Unfortunately the movie In the Little wood is not yet available on Disney Plus.