Really? Here's the excerpt from the novel, right at the point when Palps was firing lightning at Mace and had him in trouble.
Pg. 334 of the hardcover Revenge of the Sith novelization:
If you will notice, Palpatine was on the brink of destroying Mace, but with Mace pleading with Anakin for help, Palpatine figured Anakin might side with Mace so he goes DIRECTLY from dominating Mace to the point Mace says "Anakin, he's too strong for me...", to becoming that feeble old man.
So Nurb, I'd say the novelization does make it quite obvious that Palpatine "gave up" in his fight because he didn't want to risk having Anakin side with Mace at that moment. That excerpt, atleast, definitely points to it.
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palpatine was the one pleading for help, not mace windu.