I don't think you have to like losing but you have to accept the fact that you lost and also that you were beaten. You can find excuses but really, that doesn't help. It's good to understand why you lost and what you need to do to correct those things but that's where it stops for me.
I've always kinda liked the last scene in Rounders. I won't post it because of the language I'll try to recap it. In that scene, Mike McDermott (Matt Damon) is playing Teddy KGB (John Malkovich) in Teddy's club. KGB is beating Mike McDermott. He sets the hook by losing the first 10K to get McDermott even with his debt and then baits him. McDermott does what he knows he shouldn't and decides to play on. KGB is beating him pretty good, talking trash and finally McDermott figures Teddy out. He finds his tell. It rattles Teddy and McDermott comes back. The last hand is an all in where Teddy is really talking trash, he believes he has McDermott but instead, McDermott has Teddy in an all in situation. When KGB realizes that McDermott has him, he gets all pissed off, starts throwing things and basically blessing out McDermott and how he won. McDermott brings it to a fine point by asking, "Are finished because I can bust you up all night?" The enforcers start walking towards McDermott but Teddy stops them. He comes to the correct conclusions, which is, "He beat me fair and square." He goes on to tell his people to pay the man his money.
To me, this is kinda how I feel about winning and losing. You don't have to like it. In fact, I probably have no use for you if you are OK with it but you have to acknowledge the fact that you got beat and learn from it. Be a professional about it.