I don't generally like blue on walls, but this looks fresh, not cold. Love the red sofa.
Red Couch Living Room. Coral Pillows. Modern Farmhouse
Or do I go with grey walls, since that's the other dominant color in the paintings? (well, black/grey)
Not sure about gray on the walls, but I like the overall color scheme!
39 Red And Grey Home Decorating Ideas | Decorating Ideas
living room red sofa nyc diana mui interior design west elm box frame basic coffee table
maning6 - Contemporary - Living Room - Images by Willow Tree Interiors | Wayfair
brown and gray color scheme - small amounts of red couch brown walls gray trim off white.
Whitehall - Camden, Maine | Rachel Reider Interiors
how to decorate with a red couch - Google Search