To me, I don't think Kate had plans on splitting - ever. She probably thought in her mind that they were just a bickering couple, but she did say that it got to the point where it was really nasty. You wish people could bite their tongues and not fight in front of the kids, but the stress becomes way too much and words fly.
Kate has said she was stunned when they separated and Jon said the same thing. He kept asking himself "Why, what went wrong" (in his words in interviews). I tend to side with Jon on that one - he probably didn't see it coming. Kate probably got to the point where she gave him an ultimatum and he did not go along with it - hence the split. So they were both pretty stunned when they went their separate ways.
Hopefully Jon can become a responsible human being and transform into a hermit for the next few months. Stay out of the spotlight, get rid of the girls and focus on being a good Father. That's what's most important. If he says one more time that he needs to apologize and make things right (with EVERYONE), I'm going to scream. Quit doing interviews and quit saying that. Just do it!
Jon lies so much, he can't keep track of what he's told to so many people. Even his little girlfriend has said it on the Insider. I think he has a problem. My husband who does not watch regularly said he always thought Jon was a good guy, but even he shakes his head now and asks what's wrong with him. He needs serious changes in his life.