Most girls names that are sometimes called "frilly" have a romantic sound to me eg. Georgiana, Christabel, Isabella, Arabella, Anastasia etc
Also names of famous romantic heroines eg. Lara, Lorna, Rose, Tess, Rosamund, Corisande, Juliet, Isolde, Cressida, Guinevere etc
Boys names are harder - some of the Welsh ones sound quite romantic to me : Tristan, Dylan, Evan, Osian, Emrys etc
Or names with softer sounds or from romantic books - Hugh, Henry, Noah, Maxim, Gabriel, Nathaniel, Laurence, Sebastian etc