i think it's interesting how Scorsese tries to convey Katya's psychological state throughout the movie. before her father died, she wasn't seen with a single black clothing item, however after that, she always had something black with her, highlighting her grief and her guilt. she wears scarves and sunglasses a lot, always wears dark lipsticks and extravagant updos. she wears her clothes like armor and is always trying convey power and fear. EXCEPT when she is alone with Sofia. when they're together, Katya still wears her warm fiery colors; red, orange, brown and gold. but they're lighter and brighter, and her lipsticks are in softer colors. she looses the scarves and sunglasses. Katya doesn't want to scare Sofia, she doesn't want power over Sofia. she just wants Sofia.
which brings me of course, to the boat scene, when Katya is still dressed up with her whole armor (after that whole deal went down that i won't get into) and it's the first time Sofia actually understands the layers of Katya Goncharov, who she is and who she had to become to survive. and instead of judging her, Sofia gently lifts Katya's sunglasses and place them over her head and says "there you go. you're too beautiful to hide your face like this." in the same tone as she talked to her in the apple stand scene, softly touching her in the same way, when we know Katya showing her face around in the apple stand was the reason the "killer" managed to track her, find her and then get to her and attempt murder as soon as Sofia left.
maybe I am reading too much into subtext but i think that's the movie telling us that Katya would "show her face" and stop hiding her feelings for Sofia, if it wasn't for the killer. but the killer is not just a person, he is a symbol of a man. The Man. the patriarchal culture she lived in. with Sofia, she was safe and she could be herself, but if Goncharov had a happy ending, it wouldn't be Goncharov
