please choose the answer below....
A) Rin and kakashi are both zetsu clones. it is just to make obito change his mind to become evil after seeing kakashi broke his promise to take care RIN.
B) Rin and kakashi are trapped in hidden mist genjutsu... making them unable to control themself to tight each other.
C) Rin is a traitor.
D) Kakashi and rin are trapped in the Mist jutsu ( same as zabuza using - making the place fill with mist and make harder to see) - so kakashi mistaken stabbed rin (assuming rin was Mist ninja.
E) (post ur own anser)