How to tell a guy he's a **** without sounding psycho?

Lol weird question I know. I almost started dating my best guy friend until he told me he doesn't want a girlfriend and basically listed all the reasons we wouldn't work despite telling me he likes me. I just feel like he's been a total prick to me and he should realise that this relationship wouldn't be like his last awful one but I'm not gonna wait around forever for him to be ready. So don't really know how to put all that into words..any suggestions of how you would say it if you were me?