Unfortunately, many VNs completely fuck up romance in my opinion, by following a set, strict formula and compresses the crush phase into a matter of hours. Common routes usually take place over the course of a week, to maybe a month. Then, you enter a route, and 'OMG TRUE LOVE GAIZ!" I've really yet to see a VN that moves at a good, deliberate pace, building up two characters together so we see a relationship blossom in a far more believable manner. Clannad, should you choose to go down Nagisa's route pulls it off only due to After Story. The anime does a far better job in this sense, of creating a relationship where two characters grow together in a very real, believable manner and don't just fall in love because the story demands it. ef: A Tale of Melodies anime does this as well, through the use of a back story shared between two characters (but don't get me started on the other relationship of that season). I can't comment on the VN for that one though.
So in short Mouse, there are no good romances in VNs.