My Youth(Chinese Drama) Ep 15 - This confession was long due between the main leads.
Love Equations(Chinese Drama) Ep 13 the whole scenes leading upto the confession is just freaking cute, i bet you will just be blushing through out
Autumn Concerto(Taiwanese Drama) Ep 8 Confession scene as well as 'Baby making' moment :P
Buzzer beat(Japanese Drama) Ep 7 ending and Ep 8 the build up to this confession scene made me rewatch it for a zillion times, until i had to hard stop myself and deviate myself with other dramas. Its that amazing, but to get that intensity, you gotta watch the series
These are the ones that i can remember on top of my head. Hope this is helpful :)