What a heartfelt and bittersweet story! I love the artwork and the music, and the light/sun effects are so pretty. The sunflower animations are satisfying, and the sound effects well-placed. The quotes between acts and the backgrounds are very effective at setting the mood too.
Personal preference, but I do think some of the descriptive text between dialogue could have been cut - the visuals, dialogue, and pauses convey so much feeling on their own, the player can usually imagine how the characters are emoting or thinking with just those elements - they don't need to be told. The visual of the little flower in the snow, for instance, is so strong and impactful by itself I think having more than maybe one line of description distracts from it a bit.
Awesome job!