Chivalry was never really a thing. It was born out of the oaths that were given to knights, but with the medieval ages being a time when oaths were a common practice all over the place, there wasn't anything unique about them. Where our idea of chivalry actually comes from isn't the practices of medieval knights, but rather a popular form of literature in the late medieval ages and early renaissance. In the 15th and 16th century, it was in vogue among the newly educated and cosmopolitan nobility to write and read romance stories about heroic knights, and the writers peppered these stories with all their ideas of what a virtuous hero should be like (and they filled them with harrowing fights and romantic relationships with princesses because these were novels read for entertainment). The most famous works to come out of this is [i]Le Morte d'Arthur[/i], where we get most of the modern King Arthur story, and [i]Don Quixote[/i], which is a parody of the entire chivalry romance genre. What we call chivalry when talking about dating is more like the echo of in-fashion manners from back when women were called the "Fairer sex" because they were seen as fragile and delicate, and in need of the protective care of men, rather than the modern reading of the term that women are super hot and you gotta be nice to get with'em. 

More than anyone probably wanted to know. I'll leave it there, since 15th century literature is by leaps and bounds more interesting than dating advice.