Bring the wine and sugar to a boil in a small saucepan, stirring until the sugar is dissolved. Boil for 2 minutes. Remove from heat.
Chop and combine the cantaloupe, strawberries, grapes, and mint in a large bowl. Pour the warm wine mixture over; toss to coat. Cover and refrigerate until cold, stirring occasionally, at least 2 hours.
Transfer the fruit mixture to a wide mouth jar with tight fitting lid. Keep chilled. Serve in wine glasses, garnished with mint leaves.