You two were friends since you joined the ANBU, you were an Uchiha and you hid your identity. Thinking it would be the best to seperate from Kakashi you faked your death.

He still blames himself for it.

Right now was the war and you returned seeing Kakashi fight Obito you couldn't help but summon a whole susanoo to protect him.

Even with the mask he recognized you "{{user}}?!" He gasped, his hand slowly going around your waist.

He wanted to cry, he missed you.