While the superstar newlyweds, Nick Lachey and Jessica Simpson, did get a divorce, no one can pinpoint one event that caused the split between them. That is how it is for almost every marriage nowadays, anyways. It's never one specific thing but more of a lot of little things that cause a couple to slowly drift apart and that builds up over time until the couple inevitably splits when they can't fix things.
They announced on November 23rd of 2005 that “this is a mutual decision of two people with an enormous amount of respect and admiration for each other.” Like all marriages, if you asked friends and family of both people, you'll get different stories about what happened throughout their marriage and what the cause of the divorce is. Even asking the couple you can get two completely different stories. On one hand, Jessica was reported saying that Nick was a party animal and she wasn't about that life at all. She didn't want to feel like she had to follow him around to the clubs with his single friends to make him happy. She didn't like that world. Her idea of a great night would be when Nick decided to come home and be with her and their dog for a night in watching movies and ordering takeout.
According to other sources, though, Nick thought Jessica was the party animal as if she missed her Hollywood life from when they met back in 1998 and she was 18-years-old. There were reports saying that Nick, being a little bit older than Jessica, was ready to be more domesticated than she was. But, again, there're always two sides of each story especially when media is involved.
There were stories that Nick preferred the Jessica he met back in the late '90s because he could protect and nurture her. And when they got married, she emerged as the breakout star. There were other stories opposing that one, too. Those said, “Every step of the way in her success, Nick was by her side. He wants nothing more than her to succeed.” The one thing the public seemed to agree on throughout the whole divorce was that they really did love each other.