Addiction
Neji's not stupid.
He knows.
He knows that he's slowly killing himself with his alcohol addiction.
Neji's always been an addict.
He used to be addicted to training, vengeance and Tenten. Now he's hooked on alcohol. He tells himself his one-night stands with her are only a product of the sake he likes to drink.
Of all of Rookie Nine, she's the only one not addicted to alcohol, instead, she's committed to their nightly flings which they both know is just as dangerous.
Tenten's smart. She knows. He sees something in her eyes that night when she asks him for a sip of his sake. She is trying to move on.
He lets her have it, only because he knows either way, it will end up in bed with him.
Afterwards, he regrets his decision.
Sometimes in the back of his mind, he wonders how a healthy relationship came down to a bottle of sake.
Both you and I know…this is just a fight against addiction.