First, the standard TFP response, which somehow has been missed in this thread: "If telling your significant other that you did 'X' would cause a problem, then 'X' is cheating."
Second, intention. I'm a massage therapist. Long before that, I gave all sorts of casual massages to friends, with no sexual overtones.
Third, based on your other thread
Footsie and footjobs are fun!!!, I would guess that it would be cheating if you did this.