I saw this movie on an AirChina flight from LA to Beijing in February 2013. I think it was a Korean movie, and I thought the title was called "be my valentine". I couldn't find anything on google about it, so I'm most likely wrong about the title. Anyways, the movie is a romantic comedy and it portrays 3 couples. One teenage couple, one couple in their 20s or 30s, and an old senior couple. You think it's a movie about 3 different couples, and then you eventually find out that it's the same couple but in different stages of their lives.
One scene that cracked me up, is the guy is sitting on a bus debating on whether he should marry his girlfriend. He starts daydreaming, and pictures what his wife will look like fat and with kids down the road.
Anyways, can anybody help identify this movie? I want to buy it on dvd if possible.