Do you think Lucy Steele ever knew how bad she looked in comparison with Elinor, the only time they were all in company together?

Elinor, who truly has affection for Edward, and actual honour guiding her actions, tries to make Edward comfortable, and leaves Lucy and Edward together for long minutes.

Edward is also treated civilly by Elinor when she is half-angry with him for his initial lowness when he visits Barton (although Lucy never saw that, of course). Elinor also holds to her manners around people she does not like -- John and Fanny, Robert Ferrars, Nancy Steele -- and thereby learns things she would not have otherwise, and ensures that no ill feelings come from HER side of the relationships. Following the forms of politeness help her much more often than Marianne's disdain of it, for instance, helps her.