Aiyoo, my friend. Mood needs to be created laa. That's the difference between guys and girls. For us guys, we can get off work, eat dinner at KFC, come home, change into boxer shorts and Pagoda T-shirt, watch some Akademi Fantasia, brush teeth, then feel horny and want some lovin'. Girls cannot. They need to be in the mood. They want to be in the mood with you.

So it's up to you to create the mood. Simplest way is to take her out for a nice romantic dinner, somewhere fancy where you both have to dress up, eat some really good food, maybe have a bottle of wine with it. Advanced techniques would require more imagination.