Final answer:
The common motif shared by both the genres of epic and romance is the theme of love.
Step-by-step explanation:
Both the genres of epic and romance share a common motif, which is the theme of love. In epic poetry, love is often portrayed as the motivation behind heroic actions and the source of conflict between characters. Examples of this can be seen in the epic poems of Homer, such as The Iliad and The Odyssey, where love for a woman drives the actions of the heroes. In romance literature, love is the central focus of the story, and the plot revolves around the romantic relationships between characters. Love is explored in various ways and often results in emotional highs and lows for the characters.