In finding out that there was a tiny kitten, lost and stuck in a building, we saw its suffering and took it in, giving it a home. 

It must have suffered, as once it caught its breath, it has become a very affectionate and needy cat, meowing her sorrowful alone song until you come and see her. And when she sees you, she will follow you and climb on you, as if to say 'thank you for saving me'. We have indeed reduced the kittens suffering. 

In this same house, the cat that already lived there hisses and growls whenever she sees the kitten. She hides and will not come out for belly time or her good morning nudge, only appearing for treats. The cat, going from a stable home and known foundation to a new world with an animal she does not like or tolerates, has had her suffering increased. 

We take an action and that action reduces suffering, and that same action increases suffering as well. 

How do we navigate through such a life? If our desire is to reduce suffering, reduce unhappiness, how do we know that what we do isn't actually just increasing suffering elsewhere? 

How can one act if you know that what you will do will reduce suffering...but will increase suffering elsewhere?