Asexual people can find non-sex things very erotic, like boundary eroding types of deep communication. Most people shy away from that level of experience, but it can be quite HAWT for some... there are some forms of energy work that can be frigging intense and intimate and super crazy but not sexual in nature.

Then you have things that might be considered sexual for some people that may not actually end in a sex act. So the lines can get blurred.