My answer is No, men and women can't just be friends. At some point during the friendship one of the two will develop romantic/sexual feelings for the other (no matter how fleeting). I think many times the two CHOOSE not to ACT on them, but the feelings are there at some point during the friendship, even if for a short amount of time.
("You" speaking hypothetically) Also, you may not have had feelings for him, and he never told you he had those feelings for you (prolly because you were snoting all over his shoulder about how much you loved Mr. Wrong at the time) but I guarantee you he has had them (ONE of you had them)