why Adrian is not my friend

Thanksgving weekend is coming to the end.  On the way to pick up nanny from the Bart station, I ask my son whether he wants to go to perschool tomorrow. He replies:

"Yes, I miss my preschool. I miss Liam, Adrian and Robert."

"Who is Adrian? Is he your friend?"

"No, only Liam is my friend."

"How come Adrian is not your friend?"

"Because I have three friends. Three friends is enough for me."

"who are the three friends of yours?"

"Liam, Robert and Ethan."

"You should have a lot of friends.  You should tell Adrian that he is your friend."

"I don't like girls to be my friend."

"Why is that?"

"Because girls go to girls' room. Boys go to boys' room."

"Is Adrian a girl?"

"Yes."

"OK. case closed."