OMG thats how i am :)… i actually tell him just deal with it cuz its that time of the month :Dhe is great abt it too 
anyways i think u shld bring it up randomly (stuff abt kids and things) there is nothing wrong with that.
and tell him that ur not fasting…if he ask "why not’ just say u cant…he will understand and that will be a start for being a little more open.