She is such a sore loser; she always complains when she doesn't win.
Она такая человек, не умеющий проигрывать; она всегда жалуется, когда не выигрывает.
Definitions
A sore loser is a person who reacts negatively or with resentment when they lose a game, competition, or any situation, often displaying poor sportsmanship or unwillingness to accept defeat gracefully.
