12yo is a very poor "loser" when it comes to board games or anything competitive

Title says most of it. My stepson is 12 and is generally a very well-behaved kid. Very emotionally steady until competition is involved.He gets uber-excited to be winning at something - not necessarily gloaty but very energetic and happy. Pretty normal.But if he's not doing well, isn't the best player, or loses a game - he flips out. He'll get so upset, cry, leave the room, refuse to finish playing. In the future he will avoid playing that particular game all together.My partner and I have tried to reason with him and basically explain that you can't win 100% of the time, but it hasn't changed his behavior. It just seems odd because he is typically so even-keeled.Is there something we could do to try to curb this "sore loser" behavior? Admittedly this has been going on for several years and is only getting more intense as he gets older.Appreciate any tips you might have! via /r/Parenting https://ift.tt/34Xydpv