What should you do if the guy you like thinks you're cool but wants to be your friend only but you want to go on one date to see if that could change?

Well it is not a good thing for you if he is telling you he wants to be "friends". In guy terms this means "yeah your cool to hang out with but I couldn't see us as a couple". This doesn't mean he thinks your ugly or anything but he just doesn't want to hurt your feelings. Now as far as you wanting to go on a date, that's not a good idea because he obviously made it clear he is only interested in a friendship nothing more. nothing less. So you should keep what you already have (a friendship) rather than risking that so you'll end up with nothing. Because most guys get distant from an overbearing girl. so then you have to ask yourself "would I rather have him as a friend or nothing at all?"