I don't know how to explain it

Is it just me ... or kissing becomes normal? After awhile kissing and making out becomes just a neutral norm in the relationship and nothing different. Not saying it isn't special. But I find that when I'm away from him or can't kiss him for awhile- and when we finally can, my heart has grown fonder for such an action and all those sparks when we kiss flow back. 
How can I explain this ?? I don't want to sound harsh about this- I thought it was normal... like when you move onto doing something else intimate the last milestone isn't as exicitng as the one you're exploring