Short scenes alternate with a recurring motif of snowflakes falling in a night sky - an apt metaphor for human existence because every snowflake is unique (so are people, claims Fanny Ardant) yet they drift randomly, subject to chance ("Heads or tails?"), and melt before too long - making for a film that seems constantly suspended, lacking any firm present...
The point seems to be that coupling, as an idea, is weird and forces its participants into time warp, where past and present bleed together. Resnais uses an elliptical device that furthers this point; between each scene, he inserts a brief shot of a snowy night, though as the film progresses, the shots sometimes omit snow and are simply dark. The play with images standing in for the passage of time is direct allusion to Zorns Lemma, Hollis Frampton's mathematical alphabet film.