"Marriage has many pains, but celibacy has no pleasures." ~ Samuel Johnson
There was time when sex and reproduction posed as an existential threat to all: When the entire population, humans and animals alike, were stuck on a single, dingy, barely-afloat boat. With no shore in sight, as thunderous skies clapped; snuffing every hope of sunlight.
The captain of the ship ordered a decree, applicable to all the passengers of his overloaded ship: “NO REPRODUCTION ALLOWED UNTIL THE SHIP DOCKS! We can’t afford the extra weight. If this ship sinks, we’re done for it!”
Naturally, at the risk of sinking the entire chain of evolution, everyone refrained from canoodling. Pious or not, begrudgingly or relieved, the sexes segregated and a silence fell in the divide.
For what could possibly be more interesting than talking about sex on a doomed ship?
Anyway, nine weeks later, and right under the captain’s nose, a handful of kittens and puppies chased each other on the ship’s deck. “Hmm, that’s odd,” thought the captain, “I don’t remember bringing more than a pair of adult cats and dogs on board. Where did…no, wait…PROPHETIC OATHES!!”
Hence, for risking the survival of their fellow passengers, cats and dogs since then were cursed to copulate aloud, shameless and publicly, for ever and ever and after.