I just can't get out of my mind that the Jennifer/John dichotomy is primarily about the pairing, not about Jennifer herself, you know?

It was clear that he would do anything - and I do mean anything - to save her. Because he loves Elizabeth. I'm not even talking about romantic love; I'm talking about that fierce protectiveness that you feel for your chosen family. I think Rodney knew Elizabeth would die for him (and for all of them) and thought it would never happen. So watching it happen in front of him drove him to do something he knew she wouldn't want, just to save her life.