All voluntary trades are win-win or they wouldn't happen. Each party subjectively views their post-trade position as better than their pre-trade position.

The only time someone can 'lose' is when they are not involved in the trade.

You can also have WIN-_win situations where one side receives a much higher increase than the other party. For example, asking two people to divide $100 dollars could create a win-win situation with $99/1 or $50/50.

Win-win has a different connotation in engineering terms. It means that you have resolved apparently opposing goals by killing two birds with one stone. Everyone wins except the birds.