I have no experience of it because I didn't feel anyone were suitable for me with whom I can connect mentally. But I think it's not necessary to receive a heartbreak in a relationship if both partners are suitable even if they are not perfect.
But in your friend's case he play other people's heart means I don't think it's only fear. Who know if it's his nature.
It could be in his nature, but also sometimes, certain situations forces us to be what we're not.