I thought the Shep/Liara romance was one of the best of all times to be found anywhere and certainly in a game. It is a classic romance.
1) The hero saves the less experienced love interest.
2) The LI helps the hero fulfill her destiny.
3) The LI naturally gets a crush on the hero and the hero, seeing the LI's hidden qualities (intelligence, determination) starts to fall as well.
4) They fall in love while the hero is fulfilling her destiny.
5) Tragedy happens and the LI loses the hero.
6) Instead of being crushed, the LI helps to save the hero and becomes a much stronger person, a true partner to the hero.
7) The hero and the LI are reunited after completing some quest together and reaffirm their love.
8) The hero and the LI are torn apart by circumstances once again.
9) The hero and the LI are reunited and again reaffirm their love and finally commit to each other.
10) It is through the practical and emotional support of the LI that the hero is able to defeat the ultimate evil/enemy (ie "I do it for my love ones" "I couldn't do this without you, Liara")
While I agree that some of the dialogue in ME 3 especially is horrible because of laziness or a lack of time/money, the overall romance between these two is incredible.