Guys will open up in people they trust. That means their mum, their best friend, a girl who they consider a good friend, or yes girlfriend material. I'm different, I dump my feelings on everyone :P but experiment a little, ask him what they think about you, and tell them to be honest. If he opened up to you, he is going to be honest about this one, and make sure you say it puts no pressure on what you have either way. If you like this guy, he could be a great friend, or a boyfriend who you have fun with and then end up hurting. Guys won't say it, but they get beat up about relationships ending, they will bottle it in and it will hurt.