I've been staring at a couple in the other aisle.
Do they know you are staring at them?
Yes, I know they're aware of my presence there.
If they know you're aware of them then it's better to start a dialogue with them instead of continuing to stare. Otherwise they'll think you're creepy.
That is too bad for them.
They're probably going to want to avoid you if you keep staring. Wouldn't you rather try to talk to them instead of making people feel uncomfortable?