Sir Pelleas, Knight of Arthurian legend. Most accounts are unanimous in agreeing that he loved Lady Ettard. It seems she did not requite his love. In Malory's account, Book 4, 20 tells us that he won a joust and offered the prize of a golden circlet to Ettard, declaring his affection for her. However, she was proud and did not requite his love (according to Malory, other theorists postulate that this was because he was ugly.) She hated the sight of him so much, that when he began to follow her 'until she loved him', she sent knights out to fight with him every day.
The next few chapters follow Pelleas in his quest for the lady. The hapless fellow recruited Gawain to help him, but the latter then fell in love himself with Ettard. He told Ettard that he had killed Pelleas, which immediately put him into her good books. The long and the short of it was that these two ended up sleeping together when Pelleas stumbled in on them. And he was wroth.
At this time, Pelleas started wandering around, moping, when Nimue stumbled upon him and asked what the matter was. When he told her of his plight and his lovesicknes, she cured him, and, ardent youngster that he was, he fell in love with Nimue, and married her. Ettard later died of sorrow, which makes for a nice, well-meaning moral to this section: nice guys don't finish last.
After this happened, Malory says that Pelleas was one of four to acheive the Sangreal, and thus Book 4 ends, with Pelleas presumably living happily ever after. A rather far-fetched, although, I think, more romantic ending to the saga of Pelleas is this: that Pelleas came to be haunted later by the ghost of Ettard, and, not being able to exorcise it, found it one day beneath a tree. He promised that he would not sleep during the hauntings if they only took place by night. From this agreement onwards, Pelleas grew ambivalent toward the hauntings, and eventually fell in love with her again. At this time, the ghost disappeared. The author of this tale suggests that this is the story causing the wanderings of the knight in La Belle Dame Sans Merci by John Keats. A nice story.