Honestly, Inigo's whining comes so naturally, instinctively even, that he has absolutely no idea of the power his puppy eyes hold over the other. It's not even a tool he's using on purpose - it's just what Inigo is naturally inclined to look like when someone tries to walk away from him.

So when Gerome actually stops walking, he looks a little surprised. And then when a moment later Gerome even asks that, Inigo's eyes grow wide with the same surprise.

.. well, surprise, and also excitement.

He knows he can't respond too enthusiastically or he may just scare Gerome away again, but it's so hard to contain his excitement at Gerome giving in even when it's not happening in any gloating kind of way.

"Yes!" Inigo takes his hand off the other's shoulder so he can put it over his own heart instead. "I formally swear that I definitely will not bother you with my whining again.. for the rest of the day, anyway!"

Look, he just can't make promises about the further future...