Here’s a simple line to use any time you see a woman verbally harassing a man, or trying to maneuver him into completing a task for her where they have no established relationship.
“Oh wow, I didn’t realize you guys were dating.” Importantly the tone is playful and an element of mock surprise.
The woman usually bursts out laughing every time I’ve done it, plus they usually stop ragging on the other guy right away. It’s a big win for you in that the other guy is usually relived that you pulled the woman off him, plus you’ve effortlessly passed a fitness test she threw out. Advantage you.