FL can't choose between the ML and SML

Strong Woman Do Bong Soon has some of these elements.

Dramas

Scarlet Heart Goryeo

Kiss Me (Thailand)

In Time With You (Taiwan)

Kurosaki Kun No Iinari Ni Nante Naranai (Japanese)

Ugly Duckling series : Don't (Thailand)

Weighlifting Fairy Kim Bok Joo (i think that's just a crush)

Movies

Crazy little thing called love (Thailand)

DoReMiFaSoLaTiDo

Love Forecast

Our times (Taiwan)

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 --'