Well, I know having first love is nice and all, but do you realize how often people end up with first love for life? Rarely - it's because first love is too immature (often, not always!) and later in the life you mature and know that really matters in relationship.
And Imo, the thing which matters the most in relationship (equal partnership, supporting each other - not suppressing, acceptance of the other person as they are so they don't have to pretend to be someone else and can be themselves) is that Min Hyuk and Bong Soon already have.
I don't feel same between BS and Gook Do... :/