Lovers (stock characters)
The lovers are eiron figures, and it has been noted that they often are coloress creatures, sometimes even ingenues next to the blocking figures, the alazons who prevent their love, such as the Senex iratus or the Bad fiancé.  The Innamorati of Commedia dell'arte represent this by going unmasked in the midst of the other characters. Often, the lovers are incapable of resolving their own problems. The role of rescuing them is often a tricky slave's place.
When the lovers' problems are at least partly internal to them, they have diverged from the stock characters. Florizel and Perdita in The Winter's Tale are such lovers; Perdita's reluctance to be wooed by a man above her (apparent) birth is a trivial problem beside his father's rage at such a match. But in Much Ado About Nothing, Claudio and Hero's problems arise from Claudio's being gulled, but are not solved until Claudio shakes off the villain's influence, and so he is not the stock character; still less are Benedick and Beatrice these stock characters, where the obstacles to their love are entirely in their characters.
Northrop Frye considered this plot, with colorless characters and all, a central portion of the myth of spring, comedy.
When the romance is not the central plot element, the character with whom the hero or heroine is deepy and truly romantically involved is called the romantic love interest, beloved or sweetheart.