It has nothing to do with fighting against any other

woman. Being straightfoward is to protect yourself. If you think it a time for your to have the exclusive relationship with him, then you shall be straightforward to tell him what you want. If he agrees, then the relationship will move to the next steop, if not, tell him that you need to move on and no need to hang out with him any more. It is nothing to loose to be honest with yourself and with that man. It won't work only if you are worried about lossing him. If I were you, if he is not in any exclusive stage, move on, why worry at all? I guess you have some affection over him. That is your weakest spot.