I'm not a native english speaker, I'm from Germany so please excuse my mistakes. :)
A few days After Tony had arrived in D.C. Abby just wanted to hear Zivas voice and so she called her on her mobile phone. Abby knew that Ziva wouldn't talk to anybody, but she missed her best friend so much. And Abby was right, Zivas mobile phone wasn't even on.
So she thought of any other possibility to communicate with Ziva. Sometimes they had used a chatroom, when Ziva had been under cover, but they haven't used it for a very long time.
Despite her doubts, Ziva wouldn't even notice if she sent her a message, Abby logged in and started a chat.
A: "Ziva, I know that you don't wanna talk, but listen to what I have to say (or just read it ;)) I still hope every day that you'll come home and I won't give up my hopes. Please reply to this to show that I still matter to you. We all miss you. Abby"
Abby thought about Tony, he'd looked so desperated when he got home from Israel. They've all hoped that he could have convince Ziva to come back and that they could be a family again. But she didn't come back. Tony wasn't the same when he got back. He'd been absent and contemplative and Abby knew he had let go the girl he loves and cares the most about.
A couple of minutes later Abbys computer made a sound. A new message!
Z: "Hey Abby, I miss you all, too. But I can't come back. Sorry. And you do matter to me :)."
A: "Ziva! Oh I'm glade you don't ignore me. Dont get me wrong but I don't get it, why can't you come home? Tony's been not good since he came here, he needs you. We need you."
Z: "I would never ignore my friend. Honestely, I can't tell why. I don't know. But I do know that I have to stay here, at least for a while. I have to get myself clear."
A: "Do you know you broke Tonys heart?"
For a few minutes Ziva didn't write anything.
Z: "Yes. And I'm truly sorry."
A: "Then why did you do it?"
Z: "Idk... im sorry I can't give you the answers you want."
A: "Ok, as you don't know why you did it I'll tell you what exactly you did. Tony's going to hell when you're not with him. He's in so much pain. He needs you to stay alive. Tony would do anything for you. He would die for you. A broken heart can't be fixed."