Allen noticed, and Daia stiffens a bit.

"I... I just thought... when you said you liked me, too..."

What is he saying? He confessed, didn't he? Why does he feel compelled to answer Allen's question? He's not obligated to like him back. He's allowed to be just a friend.

"...I just thought it meant, that we could be more than friends. That... maybe I had a boyfriend, now... But, it's okay. You don't have to like me back. I mean, like me, like me. It's okay if... we're just friends..."

He doesn't want to make Allen feel guilty for basically rejecting him.