Ah... and I just remembered 2 more, a movie and a minis special drama from Taiwan:
Movie is a multi-cast/ensemble and multi plots story, movie titles is Love and it came out in 2012. the plot with the cheating on BFF with the other girl's Boyfriend is one with Ivy Chen as an introverted girl that had ONS with Eddie Peng who is Amber KOU'S boyfriend. I think she got accidentally pregnant.
The 2nd one is a drama special title Love in Sandstorm. The story is also ensemble and multi-plot. The middle child (the parents have 3 chikdren) and only girl got drunk and accidentally had sex with the guy her best friend likes and kinda is dating. though the guy is just playing around with her best friend. I love this drama. Watched it last year, and definitely this is one of my faves...