Although I do think that romantic love can be, and usually is, associated with physical desire and sex, it doesn't necessarily have to be, but it differs from platonic love in the sense that it appears unique to the individual, that no-one could ever quite fill the void that your love mate would leave whereas platonic love doesn't have any of the lustful characteristics or singularity of romantic love, that is you could platonically love many many people, whereas I think more than a few romantic loves would be usual.