All is _not_ sex.

And a sexual motive is _not_ to be attributed to all human activities.

We know it, without need to argue.
Sex surely has a specific meaning.

Sex means the being divided into male and female; and the magnetic desire or impulse which puts male apart from female, in a negative or sundering magnetism, but which also draws male and female together in a long and infinitely varied approach towards the critical act of coition.

Sex without the consummating act of coition is never quite sex, in human relationships: just as a eunuch is never quite a man.