Falling in love is like trekking a harsh mountain road without any gear. Shikamaru can't help but agree to that. So, he vowed to never fall in love with anyone.
However, his views in life slowly crumbled as he began to be more affliated with Konoha's No. 1 knucklehead ninja, Uzumaki Naruto. The most confusing person he had ever met.
It was said that Nara's like puzzle, especially hard ones. So when he noticed himself wanting to know more about the hyperactive blond, he reasoned that yes, Naruto was one hell of a hard puzzle.
But as years grew by of him openly, and secretly, digging information about him, he arrived at a different answer. He loved the blond; and immensely so, by the looks of it. It came to him one afternoon one year after Naruto had gone with Jiraiya to train outside of Konoha.
He was laying by the meadow, watching clouds as always, when his thoughts drifted into the few information he had about Naruto; when a question suddenly drifted into his mind. Why did he care anyways? And that led into more confusing thoughts, which gave birth to this one particular thought; When was I reduced into a lovesick pup-
And he sat up after that, his thoughts running wild. But he had to admit that Naruto really is beautiful. Cerulean eyes, and almost feminine features, definitely beautiful. Not that he was the only one to notice. There were others too, Kiba and Neji to name a few. And then there was Sasuke. That guy was the reason of all this.
It hurt to say this himself, but that arrogant man was half the reason why Naruto is so strong. He was always in Naruto's mind, never letting him rest, making him stronger. It was so hard to look at Naruto and not be angry when he talks about Sasuke. All those pain he suffered because of Sasuke, yet he still wants him back. The other half is because he is just plain great.
Back to the topic at hand, Naruto really lived up to his title; doing great things now, then stupid things later on. He is childish just hours before and now, he's like the most mature person you'll ever meet.
Call him a lazy ass if you want, but he wouldn't pursue his love for Naruto, no matter how enticing the blond is at times. How he looks when he's covered in sweat and how he moans he's eating Ramen, it's sometimes enough to give him a hard on. He just hides them behind his lazy attitude.
Shikamaru, prodigy that he is, knows Naruto loves Sasuke. And that Sasuke loves him as well; added to the fact that they shared a few too many kisses with each other, if their, eyes drifting to one another when asked about their "first or second kiss" was any indication. And that Naruto made Sasuke his goal in life, not Sakura whom he declared as the one he likes.
As for Sasuke, he had his doubts of course but Naruto coming back alive from their fight at the Valley of End was enough reason for him. Surely, he could've killed Naruto when he got the chance back then, he was, after all, stronger then Naruto at that time.
So, he wouldn't purse this with Naruto. Naruto was, daresay, a great shinobi, friend, comrade and everything else that comes along with it. But he had a person that he loved, and he respects that. Also it's too troublesome to get up with the pain from his ankle. Yep, definitely the pain.