Cursed

I am incapable of platonic friendship with a male. Or rather, I become friends with males who soon feel differently. Because I'm too easy. I behave like myself and I don't set up boundaries and I'm almost "like a man" and then the relationship turns into something that I don't want. I can name one, maybe two male friends who have always been and will probably always be strictly platonic. I have hurt more guys than I can count because they fell for me and I didn't feel the same way and hurt them. The only advice I have been given to remedy such pain is to not be easy. To be guarded, shielded. How can you build a friendship on that, though?