The Arthurian Legends was an inspiration for medieval romances.
Because of the values of chivalry. The knights had honor, were brave and always were the heroes.
Scandinavian epics were sagas of Viking voyages, that's not very romantic. A bunch of Vikings pillaging villages.
Greek Mythology was mostly battling monsters. Only one story was kinda romantic, the story of the Trojan War, only because it was all over Helen.
Aesop's fables were more of moral lessons.
Hope this helps.