This is amazingly crafted.
The only thing I could criticise is that one scene, where Hazel actively pollutes the environment. Your protagonists shouldn't do such stuff, because people could learn from it. And after that, you introduce the outer world, where places & people get mentioned that really add absolutely nothing to the story. All that really matters is the snow, I guess.
Besides from that, this feels like a masterpiece to me.
It's kinda cozy, but not in a boring way. Gives me studio-ghibli-background-image-music-video-vibes. It shows an everyday scenario, which most of us can relate to. broken dreams, bad coping. I especially like all the small details you added to describe characters & their relation via the surroundings. the laptop-password, or which books lie around, how the room carries the combined style of a beautiful relationship. The characters, their actions & reactions felt incredible realistic.
I liked all the little references to nostalgic stuff.
Your building of a world, atmosphere, metaphors, characters, their relations & actions/reactions, handling of reader-emotions & your sense for dramaturgy are crazy impressive.