Isn't it handy that he got so completely distracted by one thing that he had no time to notice the other thing, Nita..

"Yeah! We're.. We're best friends, Tidus and I!" So hung up on this that he's totally oblivious to anything else here. He even releases a breath, trying to let go of some of his flustered feelings, but alas. Those tend to stick with Inigo for longer than he'd like.

"S-So no problem, you're not assuming anything at all!"