Idealistic: Considering a love relationship not meant to be is in play, it is merely a fantasy that two people from different social classes would live happy by each other, but there are those who choose to keep on believing.
Illicit: In the middle ages, people were only allowed to marry those belonging to their respective social class. Therefore the idea of a knight courting a noblewoman (married or engaged, in most cases) would be considered a crime.
Brave: It takes courage to pursue with conviction a relationship that the high classes would tolerate, condeming the lower class individual to great peril.
Courteous: It goes without saying; courtly love carries chivalrous and polite elements within it.