Okay at the risk of taking this thread back to normality, I know the answer to this as expalined by Mr Loaf himself on the Storytellers album. If you listen to the lyrics of each verse, he tells you all the things he WOULD do for love e.g. run right into hell and back and then the last line begins "but I'll never" and goes on e.g. "do it better than I do it with you" or "forget the way you feel right now" and it is that that he won't do. So he won't do it better or forget how she feels etc. Then as someone else has already said, he won't screw around as she thinks he will.
By the way, having seen him live numerous times, this is one of the best live songs he and Patti Russo do, second only to Paradise by the Dashboard Light.