After reading Nick's Rolling Stone interview and recapping the sequence of events, I am sure that Jessica divorced Nick because she wanted to get with that Maroon 5 singer. In the Biblical sense. Which she did once the ring was off her finger (she was seen coming out of his hotel a few times in the wee hours or even 10 am in the morning wearing the same clothes as the night before. Adam Levine. And he even came up to Nick and said that nothing happened between he and Jessica while she was still married! Which basically means that everything happened when the divorce was set!!
Now that that guy is out of her system, she might even come running back to Nick. I don't think he should take her back. I think he will find a nice girl who will treat him well. Jessica's too immature and wants to play the field I think.