They're officially a thing as early as Zombie Island (1998) so far off from the original iteration, but before What's New Scooby Doo which is generally well received unlike some of the Scooby dreck they've put up recently.At least you answered like normal human being xD and I thank you for that.
But, imo that pairing was only stereotype pairing, you know like cheerleader and jock are always a couple. Then again I haven't watched newer iterations of Scooby Doo I only watched the orginal one, so I might be wrong.