I have to agree with the people who have posted above: if you don't like writing romance, get someone who does or don't do it. Talk to some romance writers, perhaps - it's not the maddest suggestion in the world. Perhaps I'm being picky but it does seem to me (and, from the forums, many others) that it rather comes across that the romances in NWN2 were written with great reluctance by someone who would rather be doing something else. I guess there'd be an outcry if you cut the romance plots altogether but, personally, I'd rather have nothing than something done half-heartedly.
Also I'm not sure a list in an altogether helpful approach (but, hey, what do I know?) - the problem with romance, I think, is that it's so incredibly personal. One woman's Prince is another woman's frog. I didn't particularly like the romantic interests in NWN2 - although well voice-acted Casivir was way too angsty and his declaration came as something as a shock to me because I'd basically just ignored him. Elanee was just ... a bit ... blah? I'm sorry that's not very articulate but she was kind of grim and self-righteous and uninteresting. Also the love story such as it was had a sort of tedious inevitability to it: if you hang around with these people long enough they'll eventually decide they love you. And the influence mechanic doesn't help either. Because the only way to gain influence is, essentially, to suck up to your companions there's no sense of interaction there. Its them speaking and you trying to guess the right response.
Perhaps part of the difficulty is that romance plots in computer games tend to contain very little tension or conflict. Assuming you don't set out to sabotage them, they tend to just happen. Couldn't there be romantic rivalry? And why can't there be doomed or thwarted love stories? FF7's Aeris was a very successful tragedy, wasn't it?