What a mess. Can he say he knows what was going through Yuki's head? No--not really. Not with any certainty. There was something there unsaid, a trouble that spilled into this complicated state, and now Yuki couldn't explain his actions and what was on his mind until he (hopefully, Tidus hoped--) came back.

Love was so complicated. So was life.

"Maybe he got worried for you," Tidus remarks, putting no weight to the thought; there's really no basis for him to draw from. "I don't know the guy, but going to his world, settling down... it's a lot, you know? And you didn't do anything wrong," he states, knowing he'll need to, for whatever amount Inigo will believe it, "but, whatever you were asking him... who knows what could've been going through his head? Would you wanna stick with him when you got there? Would you change your mind and be stuck in his world? Maybe he got cold feet, I don't know. But I know he doesn't hate you."

Now Tidus looks at Inigo, as if he needs to face him with those words this time to ensure them. To make sure Inigo is hearing him.

"You both need to talk when he gets back," he says, knowing there's no other logical step to this problem. "No matter how hard it feels. You've gotta talk to each other."