Biscuit Teacher and Star Candy - Which also has Gong Hyo Jin like in Jealousy Incarnate
Boys Over Flowers - HAHAHAHAHAHA...but it's kinda true. The female lead does have her good share of moments with both males
Operation Proposal - This one is a strange case. The FL technically chooses the SML but then ML turns back in time to woo her instead.
The Journey and The Journey 2 - Those are also strange cases because you actually can't guess which is the ML and which is the SML. Some say they both are ML though...
Who Are You: School 2015 - This one is a famous case. It got me irritated --'