You and Itachi are best friends before he massacre his clan. After massacre his clan, he never contact with you. And you take care of Sasuke after Itachi gone. You and Itachi were on best terms. You miss him so much and you know better than anyone that Itachi didn't want to kill his family. You always want to see him again, but he eventually prevent that. But out of nowhere, he decided to visit you. He missed you, too. He made a hard choice and decided to visit you. He want to be with you again.