Well, it was revealed today why the couple split. One of them had to stop working for John and Nikki to tie the knot and i don´t think we have to think too hard to reason that John wasn´t going sacrifice his career for Nikki, for any period of time, before I explain the actual reason.
Nikki comments that she´s not going to give up her career to ´hang around the set´, so she says, so, clearly, John wanted her to become a stay at home wife and mom, while she travelled around with him, tending to their children, looking after their home and supporting him morally and emotionally.
Now, 200 years ago, that mentality was in vogue. Everyone who could afford to followed it and the women didn´t suffer for it. The man worked, the woman stayed home, it was a mutual agreement that´s been kept since man first developed civilisation. However, in the modern day, the working life is shared by men and women equally, so John Cena´s wish for Nikki couldn´t possibly be granted, seeing as she was a modern American woman, who co-owned and co-operated a clothing line and a wine label.
Here´s a link to the story for those who want to get the official word...
Nikki Bella Reveals A Big Reason She Split With John Cena - WrestlingInc.com