After (y/n) and Neji started dating not much changed with them. Over the month they had been dating a lot of people had found out. Because (y/n) knowing Kakashi knew she would get the talk if he found out either that or he would be extremely overprotective. So she swore Gai not to tell Kakashi. That worked out well until the night when both (y/n) and Neji were away on a jonin mission and couldn't stop it from being revealed.
Kakashi and Gai went out drinking together being the single man they are. Kakashi had at first said no because he had to look after (y/n). When he remembered that she was on a mission and would be gone for a few days. He decided why not drink to his heart content and perhaps find someone to lay with (y/n) not being home. I mean underneath even Kakashi wanted company. That night as they were drinking Gai, of course, insisted on challenging Kakashi to a drinking contest. "Hey, Kakashi my eternal rival I bet you can't drink as much as me", Gai challenged. Kakashi let out a sigh he knew where this was going. "If you can drink more cups of Sake then me I will walk fifty laps around the village on my hands"
Another one of his stupid motivation rules Kakashi thought before he got an idea. "Actually Gai I have another idea for what you will do if you lose"
"What is it Kakashi. The spirit of youth is running through me"
"If I win you have to ask out the next young person who walks into the bar no matter what gender they are. And go on a date with them", Kakashi said.
"As expected from my eternal rival challenge accepted. But I won't lose Kakashi", Gai declared.
"Nor will I", Kakashi said as he took his cup of sake and drunk it all down. Gai did the same. After around 10 or more cups of sake, Gai was so drunk that he couldn't think clearly. While Kakashi had a somewhat clear head. Mainly because on missions while he was in the anbu he had to drink with the target to gain their trust before eliminating them. So over the years, he had gotten a high tolerance for drinking. Even if he were drunk, he would never show it. Especially in front of Gai. Gai had just drink another cup of sake. Kakashi was drinking a glass of beer.
"You know Kakashi that *hic* the young generation seems to *hic* be surpassing us in finding partners *hic*. I mean a good half *hic* of the genin are already dating. Even your adoptive daughter (y/n) is dating someone *hic*", Gai said drunkenly.
"Oh she is and who may I ask is she dating?"
"Why one of my youth students Neji", Gai responded forgetting everything he had said.
"Is that so", Kakashi said.
"Yup", Gai responded drunkenly. "Now fight me *hic* Kakashi"
"Sorry Gai, not today I think you have had too much to drink", Kakashi said before taking away the sake.
"Speaking of which Kakashi *hic* what is behind that mask of yours?"
"Another mask of course"
"Oh is that so as expected of you Kakashi", Gai said drunkenly before passing out. As Kakashi got up and paid the cheek. He would remind Gai of their bet another time. For now, he needed to get Gai home before he causes damage as he sometimes would. After getting Gai to his house and making sure he was fine. Kakashi left for his apartment. Before settling on the couch and having one last beer. Asking himself when everything changed? (y/n) came back home from the mission. Kakashi was sleeping on the couch. But it didn't take long for Kakashi to attempt to have a "talk" about (y/n) and Neji. In which she literally had to threaten to burn his "novels" in order to stop. Afterward (y/n) never trusted Gai with a secret again. Especially if there was a chance that he would get drunk and spill it. While Kakashi "talk" would have to wait until another time.