Red and vulnerability

After watching the film again I noticed that there is very interesting use of the colour red in clothing, furniture and in the Streetcar Named Desire.I came to the conclusion that when a character wears a pure red (no stripes or other colours)they were emotionally vulnerable and baring their true feelings,for example every time Manuela goes to the play she wears red, Lola wears red the first time she meets her son.And obviously red is a feminine colour which is a central theme to the film. But Agrada never wears red during the film (she wears a jumper but it is striped with orange and blue as well) until right at the end when Manuela comes back to Barcelona again.I was just wondering why she would be vulnerable at this moment as Manuela is not wearing red and Huma has covered her red hair with a wig.I could be reading it completely wrong but I'd like to know if anyone else has any ideas
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'We're not sheep'-Edward Scissorhands