Because Night Fox and Rainbow are butt buddies but he's happily unaware that Rainbow is actually a guy.
I thought he would've learned from Jacky.
I remember having a dream where i was like "off to visit Night Fox!" and when i got to his house (it's like he lived next to me or something ._.) i went to his bedroom to find a girl sleeping on his lap. SHE WAS SO loving HOT!!!, and then i go and faint and dream over :(