United Kingdom, May 29 -- Nick Lachey underestimated the impact of 'Newlyweds'.

The hit reality TV series focused on Nick's marriage to Jessica Simpson and ran for three seasons between 2003 and 2005 - but Nick never imagined that it would become so popular.

The 51-year-old star - who was married to Jessica from 2002 until 2006 - told 'Richer Lives': "'Newlyweds' obviously became a huge reality show. The only one that had come out before that was 'The Osbournes', which was also a massive show. But that show was created as a vehicle to promote music.

"You know, my ex-wife had an album coming out, [I] had an album coming out, I'll do a little six-episode thing to promote the album. We had no idea it was going to take on this other life o...