Got matched up twice with a former marine with very strong grips and a will to win at all costs.
Its a good thing, really. Those frequently athletic but new to jiu-jitsu uke, sparring partners, are good for your game. They are good for your game the same way trying to handle a wrestler would be. They move in a different way than you expect, and you can also work on things you wouldn’t normally get away with. Work on your butterfly guard, let them pass your guard and work on your recomposing. Just watch out for the flailing limbs and the occasional headlock. You’ll be fine.