3.
Shame , Fantasy, Taboo Driven
The more dirty or "wrong" something is, the hotter it is. For you, it's more the thrill of the chase, the fantasy, and threat growing larger and larger, though *acting* on any of these impulses or fantasies may be too much. Part of the fun is acting in fantasy world and knowing there are many limits to be tested without actually fulfilling them. There is taboo in shame. While you may never act upon any of these items, it is the idea how out of character it is that turns you on.
You may enjoy being pushed past your own limits or outside of your comfort zone when done in the safety of someone you trust.