Partially because I'm interested to see if there really is anything that makes "love" as I understand it any different than a very close friendship - if not, then just one more person to be close to in a way I'm familiar with!
Also, there's an expected permanence to romantic relationships, true, less so than in past days, but still... in elementary school, there was "best friends forever," but once you hit adolescence and adulthood, you're expected to be looking for your One True Love... or that's how it seemed. Took me a while to figure out that the rules had changed. Still, I do want that bond with someone, and I'd sorta like to be able to prove the cynics, and my observations and family history, wrong, and make things work out with someone despite the obstacles.
Lastly, after a certain point, it became weird and even unacceptable to hug my friends or otherwise be bodily close. No, I don't mean sex (me being asexual and all), but that's what people inferred from my being clingy. I want to have some sort of relationship where I can be cuddly and it won't come off as weird.
That's really what I can think of right now. I didn't articulate it very well, and there's probably more, but I'll edit it later if I feel the need.