Simpson reveals her in her new tell-all memoir "Open Book" that their young union came with a lot of strife.
She was just 22 years old and Lachey, known for being in the boy band 98 Degrees, was 29. Simpson recalled how her father, Joe, asked her right before they were going to walk down the aisle if this is what she truly wanted. He felt she was too young.
Soon after they tied the knot in 2002, the couple started their MTV reality television which ran from 2003 to 2005. Simpson says the public scrutiny and her own growing success caused stress in the marriage.
"I would watch episodes back and I didn't like what I saw,'' she told Hoda Kotb on the "TODAY" show Wednesday. "I saw what people were laughing at and what was loving about it, but I also saw a lot of eye-rolling, and that wasn't just editing."
According to Simpson, who is 39 years old now, one contentious moment was when she posed for the cover of Rolling Stone magazine solo.
"He was supposed to be on the cover with me, and they were like no," she described. "I felt a lot of resentment. I felt that the love wasn't enough. I'm not a liar. I cannot stay in something and play a role. I've tried it many times in my life and I just can't do it."
In book passages published by People magazine, she explained: "I couldn't lie to our fans and give somebody hope that we were the perfect golden couple," she said.
“We were young and pioneering our way through reality television, always miced and always on,” Simpson explains. “We worked and we were great at it but when it came time to being alone, we weren’t great at it anymore.”
Simpson continued: “We really got crushed by the media and by ourselves. I couldn’t lie to our fans and I couldn’t give somebody hope that we were this perfect golden couple.”
The fashion designer went on to marry former NFL player Eric Johnson and they have three kids: Max, Ace, and Birdie. While Lachey married Vanessa Minnillo and they also have three kids.
Simpson said she hopes to help her fans by sharing her experiences.
"It's about walking through fear and it being okay to be afraid,'' she stated. "And the other side of fear is what's so beautiful. That's when you get the reward."
“Open Book” is slated for release on Feb. 4.