In a large pitcher, combine the rosé, Triple Sec and desired sweetener. Add the raspberries, watermelon, peach and lime and stir gently to combine. Chill for 3 to 4 hours. Serve over ice with plenty of fruit in each glass.
Notes
To make your own simple syrup, add equal amounts of sugar and water to a saucepan. Heat and stir until the sugar is dissolved. Let cool before using.
If you want to expand the servings for the sangria, add a couple of cups of club soda just before serving. This will make it a "sparkling" sangria.