[H]ow does one party being better off imply that some other party is worse off? If you were a partner in a business growing at 5% a year, and your income grew

[H]ow does one party being better off imply that some other party is worse off? If you were a partner in a business growing at 5% a year, and your income grew only 1% while your partner's grew 10%, would you let him get away with pointing out that you're better off than last year?