carry a torch for

1. To be infatuated with: “Frank may be engaged to Helen, but I think he still carries a torch for Laura.”

Idioms and Phrases

Also, carry the torch for. Continue to feel the pain of unreciprocated love for, as in Jane has been carrying the torch for Bill for at least a year. The torch in this term alludes to the heat of love or passion. [1920s]