Why pretend? That's just lying and being dishonest. Also even if you're happy for them it's ok to feel bad that you didn't win? Like, I don't see the good part in "pretending to be who you're not". It's not like he started yelling and throwing stuff? He wasn't even disrespectful, just couldn't keep his emotions in... Also because they were pretty much in a relationship at this point it's even worse to be dishonest. Trust/honesty is the most important thing in a relationship. It just wouldn't work out of you keep your emotions in and lie to your partner...
It has nothing to do with who u r, it’s okay to get upset for not winning but you don’t have to show that your depressed about this in front of your colleagues and friends at least one member of their group won he just made her feel worse by acting like that should at least congrats who ever won he totally ruined the mood by him acting childish
I understand being upset about not being the one to win the competition but you should still be happy or pretend to be happy for your group member.