Are you being genuine? I'm going to avoid the portion about race and focus on the other bits. If a girl is in a relationship, happy or not happy, it is never right to overstep your boundary. It is nothing personal against you, but she simply is taken. If you've been infatuated with her for a year and a half, try to figure out why. If you haven't actually talked with her in depth, maybe you're creating false ideas about her and really you're just looking for a gal in general, which you can find in time. Best of luck.