The kiss Gai gives her in return is warm, loving, and most of all relieved-- possibly a strange emotion to be feeling after that revelation, but there is decided relief in knowing that there's nothing left that's hidden from each other. This is, right now, the most honest he's ever been with her or anyone else. He's bared his soul to her and she to him and nothing has changed because of it.

He hadn't been 100% sure that he really knew what love was before. But now... now he does.