Is it your male friend that's looking for advice? What does he mean "hasn't a romantic bone in his body"? He proposed, didn't he?
Romance means different things to different people. For some women it's chocs-and-flowers, for others it's hillwalking or bowling together, or him telling her she's got a lovely smile or a great This post will be deleted if not edited to remove bad language, or watching horror movies and hiding her head in his shoulder at the scary bit, or having him do the dishes while she has a bath. So my advice to him would be - ask her! What does she see as romantic? And then do it.
(Or if he wanted to be sneaky, ask her best friend or sister).