Well, she was tempting him. But Ratchet is pretty darn smart at the end of the game. He doesnt do anything unjustifiable, dispite his circumstances. As Clank said: "We cannot dweel on what we should have done. Some things are simply out of our control."
"So we fix our eyes not on what is seen, but on what is unseen, since what is seen is temporary, but what is unseen is eternal."