As presented in the source material, Belle (named “Beauty” in the original story) and Psyche are the “youngest and prettiest of three sisters.” Both characters are forced (or nearly forced) into close romantic proximity with a “beastly” figure (via Owlcation). Belle surrenders herself to imprisonment by the Beast so as to save her father from captivity. The Beast continuously asks an aggravated Belle for marriage, who refuses initially but eventually grows attached to him. In the Greek tale, a jealous Venus intends to have her son Cupid make Psyche fall in love with the “ugliest creature” in existence, which per her intent was a winged serpent. 

The smitten Cupid disobeys her and instead imprisons Psyche. As he only visits her while shrouded in darkness, she subsequently comes to believe he is the monster in question. (She learned of this potential fate through an oracle.) Like Belle, she too eventually falls for her captor in what modern readers may identify as an unromantic form of Stockholm syndrome.

An alternate interpretation noted by The Guardian, however, is one of renewed agency. The idea here is that the concluding romances of both stories are ultimately the will of the central female protagonists, since each seeks out her respective jailer again once freed.