Gai always says "I love you" to Kakashi, but never expects it back. it has been like this since they started dated, even a while before that.
gai tells kakashi that he loves him, kakashi pauses and says "thank you, gai" while looking into hid eyes with a soft expression. this is his way of saying it back.
the handful of times kakashi did say it back, though, gai had been overjoyed, and he still remembers each moment clearly
a/n; i thought of this while looking through kakashi and gai fanart
