>>346947230
Sorry to hear that man. Honestly you should tell him anyway. No joke; it's better than bottling this up since you can bottle this up for a long ass time. Make it clear you know he's in a relationship and it's awkward but you want to get it off your chest. Chances are the dude goes through relationships like tissues so you'll get next in line. 
Also it helps for some closure. You can move on.