Big guys can just use what a large friend of mine used to call the "Amoeba technique" and simply envelop the small person to the floor, after which speed and quick reflexes are much less helpful to the small guy.
valuable lesson during my own wrestling days - 300lbs+ is waaaaay above my weight class, and I will take any advantage I can get.
As for the female participant - yes, she should be kept in view at all times. In this case, it is entirely likely that she would come to the aid of her boyfriend. Heck, there have been times that women who, having been beaten 5 minutes beforehand will turn on their "rescuer" in an attempt to back up their assailant/significant other