I feel like the story shifted between her before she found out about him cheating and her after the fact. The dark sweater is her before. All the scenes where they are interacting normally and then the scenes where she is wearing white are the scenes after. The scene where she knocks the plate off the table is her imagining him there which is why he seems unresponsive to her outburst. She climbs the stairs and falls asleep in her bed, dreaming of a better place (the ocean for her) and wishes to get over him. It's obviously killing her that he cheated. Also, it seems like her go-to place is the ocean or anything with water. "I, Rain, Why, Starlight and now 11:11" all have scenes with water. It must be symbolic for her.