In Sir Gawain and the Green Knight, lines that denote friendship are:
In both of these quotes, it is the friendship that the king feels to have a feast in Gawain's honor, and it is sorrow in the hearts of his friends—his fellow knights—that cause them to fear for Gawain's safety when he leaves them to travel to the Green Chapel to face the Green Knight.
"By Peter," said the porter, "be perfectly sure
that you, Lord, are welcome as long as you like!"
Then swift-paced the porter moved to approach him,
and others came with him to welcome their guest.
They dropped the great drawbridge, then drawing near proudly,
they bowed, their knees bent upon the bare earth
to one whom they welcomed as worthy of honor.
In the example above from Book Two, those who work at Bertilak's castle, as well as the lord himself, offer Gawain friendship and hospitality.
Generosity is seen with the following:
And then a rich robe was thrown around him
of brilliant, gaily embroidered silk
filled out with fur: the finest of pelts,
and every bit ermine, even the hood.
Thus he sat, relaxed and in lavish splendor,
till he felt far better in the fire's warmth.
And Gawain, I give you this belt, / As green as my gown...Keep this token for chivalrous / Men to know your adventure at the green Chapel.
Generosity is seen at the hands of Bertilak, his wife and his servants. They welcome Gawain gladly and care for him as a guest, as a friend of the castle.
Friendship is seen primarily with Gawain and his friends at Arthur's court, though I would suggest, too, that the Green Knight's forgiveness and admiration offer friendship as well.