One surefire color combination when you have a brown sofa and white walls is to choose a lovely medium gray curtain
Another option when you have a brown couch (look at this lovely two-tone couch here) is to choose a beige curtain.
Tan curtains are a real show-stopper in this brown sofa and gray wall color combination.
As you can see, there is an abundance of colors that can pair with a brown couch.
Red with brown