The way I see this playing out (purely from my own overactive imagination) is Hook will brood things over for a while. Emma will wonder what’s wrong/will become more interested in him now that he’s stopped invading her personal space every 5 minutes.
Hook will eventually decide to tell her. He’ll confront Emma. But Emma will misinterpret things.
Emma: “What’s wrong?”
Hook: “There’s something I have to tell you….”
(Hook is silent for a while as he struggles to think of a non-ridiculous-sounding way to explain that his lips are cursed.)
Emma: “It’s ok, I know.” *Kisses him*
Then Emma will lose her powers and they’ll have to find a way to fix that in time for the seasons finale.