There are kind of two different questions here.

First of all yes, humans are pretty good at telling whether someone is looking them directly in the eyes or not. So if you were to ask someone directly whether you are looking in their eyes or some other part of the face, they would probably be right most of the time.

The second part is whether they would notice it consciously without bring asked. That’s a little trickier. I suspect if you were staring directly at some other part of their face, people might get self conscious (do I have a zit? Is my nose that huge?) But looking at a spot between their eyes, or shiftng your gaze periodically would probably fly under the radar.

I love Biscoff cookies, but had never had them outside of a snack on a plane either. First time I realized they sold them at stores was when my local Costco started carrying them in giant boxes, which is a little like being Sir Gallahad the Chaste, and stumbling into the castle Anthrax.

Aldi has a pretty goof knockoff version in normal size packages if you have problems with moderation 😉

But to answer your question, a long time ago, my wife and I did the “Love you”, “Love you too”, “Love you… three?” thing, and apparently got up to 5 before we decided it was silly. Many years later, “Love you five” is the normal response to “Love you”.