It has almost nothing creatively in common with sex scenes in almost any other movie ever made, which are usually (lazily, and often misogynistically) used to cheaply bond the damsel to the hero.
It's not a sex scene; it is fully and completely a love scene.
I can think of so few like it.
> It's also one of the most notorious sex scenes in cinema from that era, with persistent rumors that Sutherland and Christie actually were doing the deed.
Persistent, infantile, somewhat misogynistic rumours.