Both couples are main since they are the protagonists of their own arc. But yeah the second couple is way more interesting than the first,and i love how the author was giving us hints for taehwan and yeonwu being weird during the first half of the first arc xD
nah dojin and taehee are way better for me
Ok^^
And the way they made them suspicious in the first season then becoming the official 2nd couple in the 2nd season is just ε=ε=(ノ≧∇≦)ノ
I love how second couples devour more the story than the main couples (≧∀≦)