There are 3 places in China I'd recommend to go spend time with someone special on V-Day.
Check it:
1) Houhai. Houhai is a lake in central Beijing. It's lined with bars, cafes, restaurants, and small gift shops. Take a walk around the lake or get into one of the horse-drawn carriages that pass by. And, do it in the evening.
Here's a picture I took of Houhai, frozen on a January night. People were ice-skating on it:

2) The Bund, Shanghai. Take a boat ride on the Huangpu River alongside the Bund. The last time I went, I paid a little extra to get onto the front deck of the boat. No one was there, but the two of us. You'll see many of the old style European buildings along the route, as well as the modern skyscrapers, giving you contrast between past and present.
3) Lover's Road, Zhuhai. Disclaimer: I've never been here. But, it's a well known romantic destination in China. I'll get over there one of these days. Has anyone here been to this place?