Polyamory is like puppies
Polyamory is like puppies. If you have one puppy and then get another, your feelings for the first don’t change. You can love both of them. And if you see a puppy in a store, you can admire how cute that puppy is too. Just like how there’s no definite limit on how many puppies you can love, love is infinite among people.
But it is also important to make sure all puppies are aware of each other and get along. If you get one puppy and then get another that you let stay at a friends house without the first puppy knowing, then it isn’t polyamory, it’s cheating.