During an afternoon outing on June 4, Nicole Richie and Joel Madden should have been enjoying some quiet mommy-daddy time away from their 6-month-old daughter, Harlow. Instead, an onlooker tells Life & Style, the two were embroiled in a huge argument. Nicole, 26, "seemed upset about something Joel had done the night before," the onlooker explains. Although a rep for Nicole denies any blowup, the onlooker claims the couple didn't hide their fight: "All the other guests saw it. It was really uncomfortable." Read more about Nicole and Joel's problems in the latest issue of Life & Style, on newsstands now!

Read more at: http://www.lifeandstylemag.com/2008/06/nicoles_meltdown.php.