This just happened to me too ! We each had 5 checkers and I had an advantage and a plan and my opponent claimed a draw. He knew he would lose and Fly or Die gave him a way out. We hadn't even moved with 5 on 5 yet.
Please go back to the 40 move and it's a draw. This is not fair.
An opponent cannot simply declare a draw just because they want to. This is not a good rule.
Draws are supposed to be mutually agreed on.
In the American Checker Federation (ACF), a tie game is declared a draw. A draw can be declared either by mutual agreement between players, through the strict 40-move rule, or if the same board position is repeated three times with the same player to move.