The divorce had fans shook, probably because it proved that we don't actually know what goes on behind closed doors — even if those doors are frequently opened for television cameras.
Every celebrity breakup comes with cheating rumors and some level of scandal, but according to Complex's interview with Newlyweds producer Sue Kolinsky, the thing that really drove these one-time sweethearts apart was the fact that they were just so different. Simpson was only 22 when she married Lachey, who was seven years older than her, and it made a world of difference.
"He was frugal, and she had excessive taste," Kolinsky told the outlet. "In the end they weren't suited for each other. The only thing they really had in common was their music. She was really young; I think he's seven years older than her. He wanted a family, and her father [Joe Simpson] thought maybe she was too young. Her father was very involved in her life."
Things are definitely different today. Lachey, who has been married to host Vanessa since 2011, now has three children. Simpson, meanwhile, has two children with football player Eric Johnson.
The differences in money management is something that Simpson definitely thinks about. She admitted in an interview with CNBC's Closing Bell that her first marriage didn't put her in a great financial situation.
"The biggest money mistakes? I don't know. For some reason I thought of my first marriage!" she told host Kelly Evans.
We'll never forget Newlyweds, but I think it's safe to say that both Simpson and Lachey are in a better place now than when they were debating "chicken or fish" for the MTV cameras.