The Knights of the Round Table express their solidarity by wearing a green girdle as Gawain does. Why does Gawain wear the green girdle?

For Gawain, then, the green girdle represents his survival. He wears the girdle which compromises his code of "honor". Gawain says he will forever wear the green girdle as a sign of his failure, "a man may hide his misdeed, but never erase it." When the other knights wear something similar, it is more of a tribute to Gawain than anything else. This transforms the green belt to a symbol of honor rather than failure.