There's some very good French places in town here, but quality has its price:
"Les Amis" in the botanic gardens, I think the best around, but too formal to call it romantic for me, although because of the incredible good service, you feel very private, as the waiters serve without you noticing they do. Foie gras is just awesome.
"L'aigle d'or" at Duxton Hotel in Chinatown, between the seedy massage parlours and the Karaoke is a excuisite little boutique hotel with an equally excellent restaurant.
"Au Petit Salut" at Jelan Merah Saga, the romantic hideaway in French style, try their Grand Marnier souffle.
"Duo" at Club street is a romantic lover's place too, but bit formal. There's more French places somehow in Club Street, Chinatown.
One of my favorites though is "Sebastien's" at greenwood avenue, the square with lots of pubs and restaurants. Although mainly expats, there is a nice ambience
Try their boeuf bourguignonne or the coq au vin there, just that the wine is so damn good, you wanna take another bottle, but... the great wine is sooo expensive...
my 2 cents,