Piece. -- School, romance, love-hate and mystery.
Kingyo club. -- school, romance, bullying. (Very good drama)
Bokura ga Ita Kouhen --(movies) school(pt 1) adult (pt 2) romance, Love triangle, lost love.
Love shuffle. --multiple couples, love confusion. (Very funny must see drama)
Sprout. -- school, romance, love rectangle. (Sweet drama)
Stand up. -- summer, school, friendship, slow romance. (Very funny must see drama)
Nagareboshi. --adult, family, love triangle.
Ikemen desu ne. -- youth, fame, gender bender, romance, love triangle
I don't know if any of these qualify as one or both ppl being dense about falling in love. I would say for some of these dramas love was an unexpected outcome. Or maybe the person or the way they fell for each other is unexpected.