Books for teenage girls about romance?

noughts and crosses.... its about theses two people who have been best friends from childhood but the racism of their society effects them more and more as they get older and they try and fight it. the people are called callum, who is a nought and the noughts are cled lower in society and sephy who is a cross and are treated a million times better..thats only the first book...there is a series but the other books are a bit different...might not be what your looking for but a good series anyways.