it's not so much that the addict is addicted to the physical act itself,is more using the person to fix their feelings.
this is how all addiction works wether it's a substance,person or activity.

Addiction is only classified when it becomes unmanagable,it takes precedance over every other aspect of your life.
So in that case,yes sex can be an addiction....gonna wanna throw in drugs,shopping,sports and pretty much anything else really.

anyways,back to sexbook ninja