A Film Title Question

[Tethered Kite]

Maybe there's someone reading who can help me identify a film I once saw on late night TV. It may have been made in the Sixties or Seventies. I have very little information to offer unfortunately.

IIRC there was a single setting - a cottage in the woods. It took place at night over a period of time and I believe there were only two protagonists.

I keep thinking the male lead was Malcolm McDowell or someone who resembled him. I remember the female lead as dark-haired.

The woman seemed to be living in the cottage and she'd be visited by this man at night. Sometimes the encounters were pleasant and sometimes conflicted. It was some kind of a mind game that the two were playing and it became difficult to discern what their exact relationship was. There was an element of psychological sadism and it remained indeterminate who actually had the upper hand.

Maybe at the end it turned out that one of them was a space alien?

I keep thinking the word visitor was in the title.

Ring a bell with any film buffs out there?