Why does my girlfriend (22F) get upset when I rub my feet on her while we're lying down? I'm 27M.

When we sit on the couch in the evenings, she positions herself at one end while I lie down with my head at the opposite end. Being 6'3", my feet reach her. I have a habit of "Cricketing" at night, which is the rhythmic rubbing of my feet together—something I often do without realizing it as I try to relax or fall asleep. She has brought it up several times and explained why it bothers her, and I genuinely try to be aware of it. However, I often don’t even realize I'm “Cricketing” against her leg. She also says I do it in bed, which I am completely oblivious to as well. Does anyone else experience this? Is there a way for me to stop, or perhaps a way for her to appreciate it?