The Mile High Club is over 100 years old. The very first couple to try it were using a Curtiss Flying Boat C‑2 off Long Island. The woman was cheating on her husband who was serving abroad in World War I. They managed to disengage the autopilot while engaged in their congress, sending the plane into the water. They were found naked by duck hunters.
Fortunately things didn’t go that far before this video ended, but the sentiment is certainly there. Usually passengers try to discretely join each other in the lavatory.
Here they’re just happy to be seated next to each other.
Love is a wonderful thing, and the excitement of a new and budding relationship is a feeling few people can match with their other experiences. Still, my recommendation would be for a discrete trip to the lav if you must and not to do this inflight (or during the boarding process).