if you can tell us what things you two enjoy, that will help.
having said that though, i kinda stuck and have no answers..

are there really no place nice enough here??
Viet Lang restaurant?
bum boat (rent the whole boat for you two)?
the peak of Bukit Timah??

:D:D:D
Changi chapel? (eeek)
rent the field on top of Marina Barrage, so there will be only you two?
if only we can see the auroras from singapore, then the top of mount faber willt do
