He can't help but let out a breath he didn't quite realise he was holding in when Sizhui says that last part. Like he's deflating some sort of tension, almost.

"How could I ever be upset with you?"

Sizhui is just such a sweet guy, it feels impossible to be mad at him. He could stab Inigo in the chest and Inigo would probably thank him for it. That level of impossible.

"I.. I mean, I guess that's why Jumblie let you in.." Even though she is still a dirty traitor.. "Because she knew I wouldn't mind you being here."

There's a pause where Inigo seems to realise he might have to elaborate a bit more on that, adding an awkward: "S-She's connected to my heart. And so to my thoughts and feelings."