Choosing his wife and kids in and of itself isn't weak, but Ted didn't choose them because he truly wished to remain or to do the right thing. Ted tasted the forbidden fruit with Peggy, got her hopes up, and then conveniently decided he had to "do the right thing" just after "getting some." He chose his wife out of fear of stirring the pot. It's fine that he wants his wife. It's laudable, but he decides this after he leads Peggy on and conveniently just right after he gets her into bed the first time. It comes across as spineless. I'm big enough to have an affair and tell the other woman I'm in love with her.....but I can't pull the trigger. Ted wants to leave his wife, but he's too scared to do it. If you're too scared, don't start up with someone else.