It seems to me that that stems from a design policy rather than the writing itself. Perhaps developers should approach romances more as a secret side quest, rather than a main feature of RPGs. With this in mind, romances should be made easier to screw up (you say the wrong thing, and you're done), and also, the PC should choose who he/she wants to romance. This should make things seem a little bit more open-ended and not as scripted as they usually are. The problem with this approach is, of course that a lot of development time/money is spent on something that in the end, won't be experienced by most players of the game.