Many cats tolerate or even like Dogs; many dogs reciprocate with cats, as well...so thats not an excuse.
BUT....There are two (count 'em) humans in the relationship. Pushing for a dog when your partner doesn't want one may unintentionally threaten that relationship. You already know your SO is opposed to the presence of a dog. What, then, do you think will happen when he/she catches you with the critter? Because he/she WILL catch you. You'll get careless, tired, or drunk some night, and engage enough to let your secret life out....and when you do, the relationship is DEAD. Worse....in most places, you could be jailed, the dog COULD be euthanized....at the least, your SO will give the dog to a shelter, while you languish in the legal system....This is what youre willing to risk for a little game of Doggie Slap-and-tickle? You'd better be sure because this isnt even "worst case Scenario". If your mate owns a Gun, both you and the dog could end up on a Slab in a local morgue. The SO and the dog will pay the Bill for your gratified foolish libido. Think about consequences... NO HUMAN ACT comes free of them.