The 22-year-old, who has been dating Coker for a while now, spent time alone on the set of his latest film "Kill Your Darlings", writing poems to Coker, reported Sun Online.
Radcliffe met Cocker on set of the last "Harry Potter" film where she worked as a production assistant.
The actor is currently busy shooting "Kill Your Darlings" directed by John Krokidas, in New York, and will be playing the part of poet Allen Ginsberg.