"Secret crush" is probably the closest, but it's a phrase used mostly by teenage girls. It may sound a little strange coming from anyone else. "Unrequited love" is perfectly fine. It actually doesn't say whether the other person is aware or not. It does mean that the other person doesn't return your love, but it doesn't say why. It could very well be because they don't know about your feelings.

you have a secret crush on this person. Also, I don't think anyone says "one-sided love." At least I've never heard anyone say that. The actual term would be "unrequitted love" but that's not what you're asking -- "unrequitted love" means you love someone, but that person doesn't reciprocate. But, most likely that person knows you love him.

I'm going to sound old here, but if the love is one way only, it's not love, it's a crush. Once you experience the thrill of love when the other person loves you back just as strong, you'll never settle for anything else.

Unrequited love.

the person who is secretly in love with the other person is commonly known as a "secret admirer".