Romantic courtesy is a liturgy of service which springs from the veneration of the Lady. Its goal is simply the lady’s felicity, and her looks and gestures are signs of acceptable service. All veneration is a selfless art, requiring patience, constancy, and discipline — in short, virtue. Eros may or may not attend.
The high art of courtesy requires, above all, a gentle heart, but this “aristocracy of the gentle heart” is not passivity. Rather, it is an honoring of the fair sweetheart by carefulness with subtleties — carefulness and rapt attention. The tone is attention, rather than the languor of the bower.
The lady owes similar carefulness to her lord, and will seek his felicity. However, our written records of chivalry omit her devotion and may allow a one sided view to be taken for an entire relationship.
There is also a kind of courtesy, called by Maurice Valency “heroic”, which resembles in some language and externals the romantic kind, but is quite different. This “courtesy” is actually courtship, a mutual negotiation of the terms of erotic pleasure, and so has gratification as its object. It is hardly selfless. Disciplined devotion may be required to overcome the coquetry of the lady, but we all know how easily this devotion is killed by both success and failure.