Bittersweet (Hwall X Heejin)

Just follow the rule then your life will happily ever after, but happiness is so expensive, you must sacrifice your own feeling.

Rules number 1, don't get any closer to boy/girl more than a friend
Rules number 2 let's not fall in love
Rules number 3 don't tell anyone who is yours future wife / husband
Rules number 4 back to the 1,2,and, 3

love, felt like we'll suffer. you'll feel so painful, mad, jealous, lonely also happy.