Wear sneakers during sex?
My husband and I sometimes end up shifting forward too much when he's penetrating me, due to physics of repeated thrusting. I'm guessing it's also an age-related thing too because of our muscles or balancing. If he's standing he's found out that wearing sneakers keeps him in place better because of the rubber bottoms. Then he can help hold me in place easier too. Don't know if that will help anyone else!