I read La Corda d'oro a long time ago, and watched the anime (which was obviously not as good as the manga, and I need a new manga to read that's just as romantic. I completely fell in love with that book, and I was so devastated when I got to the end, because it doesn't actually say whether Kahoko gets together with any of them. (I assume she'd choose Len, just because it was sort of headed in that direction...) but even Lili was pissed that they didn't kiss! I need a new favorite Manga that has the same sort of romance in it... but actually lasts past the confession.
I have a Sci-Fi J-Drama for you about a love triangle between a woman, her boss... and her robot. It is one of the few J-Dramas that has ever made me laugh and cry. It is Zettai Kareshi (Absolute/Perfect Boyfriend) and the episodes are like 45 minutes long (I think), so it's best to space it out over a week or so.
It's on the softer side of SF for things like the happiness sensor, but it's actually somewhat harder SF for machines with components that function similarly to how our brains do (actually theoretical Computer Science states that we ARE biological machines blah blah blah).
There is a manga version of it as well, but I have never read the manga.
Anyway, this is a romantic comedy I once cited for a Human Computer Interaction class (an online homework discussion/debate regarding the capabilities of sensors and activity recognition, but I still cited it). Also it is my current all time favorite J-Drama, so please consider it!
Watch Bokura ga ita! Omg I loved that anime. It is the most romantic sh*t I've ever seen. Don't listen to anyone else's opinion, please just watch Bokura ga ita you will love it just like I did I promise! :) I pinky promise it!
... I don't watch to much anime but ... there is one that is like only 3 or 4 episodes, but it is long enough to get a good kick out of .. has a love story and all just kinda sad if you are into it, it's called "5 centimeters a second" not sure if you have already have seen it but here is a little clip of what it's like here is the link
I hope I have helped in some manner, if not then I apologize
If your looking for romantic I would definetely guarantee Mirrai Nikki (only read final manga chapter to get original ending). It's about a death game for the right to become god and one participant is obsessed with another and it's really good and thrilling, also violent.
I actually just found one myself yesterday "Uta No Prince Sama" or UtaPri it's basically the same, hot anime guys but I must warn you that the opening song discouraged a lot of viewers...you'll see why if you check it out. And the female lead has weird eyes...but there's a season two coming out soon. Hope you check it out ^.^