He does.

He starts walking behind Mirajane, already planning on the fun he was going to have. "Uh, Natsu, home is that way," Happy said, pointing.

"Go ahead and take off," Natsu said, writing in the Note as he walked, "Happy will not think anything of Natsu Dragneel sending him off when he intends to use the Note or have sexual fun with any girls, and will always go where Natsu tells him and wait patiently for him, unless Natsu actually needs his help, in which case, he will instinctively come."

Happy looked confused, but then shrugged. "Okay, whatever, just don't take too long, yeah?"

Natsu nodded and Happy walked off as Natsu kept following Mirajane until she reached a nice looking house and entered it. (Dunno where Mirajane actually lives, and couldn't find anything conclusive when I looked it up, so I'm just going with she owns a house with Lisanna, though Lisanna is still missing obviously.)

Natsu smiled as he watched Mirajane enter, and took out the Note, ready to write.