If somebody doesn't love you back, simply Get Over It, because to pursue somebody because of Unrequited Love is Stalking and you may get arrested for it. I had many, many cases where I had massive crushes on women, yet, if they rejected me once, I'd never try again, because it's not worth it.
That's something I worked out as a very young lad. If some girl had shown that she likes me, I'd give her a chance, regardless of my initial feelings for her, because sometimes rough stones can hold diamonds. Chasing after diamonds only results in deep cuts.