Personal evolution and stimuli

We may realize that we need other people to give us stimuli, this may especially be referred to our partner. It sometimes seems that your partner gives you stimuli until a certain limit, then it finishes, he has given all he had. So what can we do? What if our partner keeps evolving? Then it will be a never ending story. As he continues his journey of evolution, he will keep giving stimuli, the excitement will never die. I need not add – the same applies to us.