For me the way I see it as a guy, being friends with someone, while secretly or not so secretly holding out for something more romantically and/or sexually, is just disingenuous. It also comes across as really needy, desperate behaviour. Which, in my personal experience, is the biggest turn off for women. So you're not going to change their mind this way. The true motivations behind the "friendship" are extremely transparent and plain for everyone else to see. People can tell what's going on, you know what you're doing, the woman knows, all your mutual friends know on some level. There's a reason "orbiters" get made fun of constantly for orbiting a specific woman.

If you still want to be friends with the person you have a crush on after being rejected or realising that it can't happen for whatever reason, you're going to have to fully accept that they don't see you in that way. Then the friendship is longer based off of the idea that you can have a relationship. Failure to accept that will doom any future friendship for the reasons I've listed above. If you cant accept that, it's probably better to have less contact with the person or even stop seeing them, instead of going though the motions in some "friendship" which is built off of the idea/fantasy that you'll eventually date them.