I don't think that it will stop, but once the peacock eel gets sizeable he might fight back, I think that ctenopomas just like to bicker, it's not like he wants to kill the peacock its just something to occupy his time. My ctenopoma also goes after my tire track eel, and my current tire track is around 17 or 18", the one before was over 2' and he did the same thing. When the tiretrack gets fed up he head shakes him and it can be viciuous especially at feeding time, ctenopoma ends up looses scales but not heart I've had the combo for the length of time I had the leopard leaf 6 years he has always done it, he wants to establish dominance which can never be his. Is your peacock is getting stressed out if so I would separate them.
You could try a mirror to divert the attention my guys loves to fight with his own reflection, you could also set up caves and hides for the peacock eel that he can not get to.
As far as feeding try switching it up with some insect larve, shrimp, ect, if your worried about money buy in bulk and freeze (not earthworms, they do not defrost well)