Joel Madden has walked out on partner Nicole Richie, jetting off on a tour of Europe and Africa, and telling her not to follow, NW reports.

"Nicole planned to accompany Joel, but she was shocked when he told her tour buses weren't a good place for her or their baby," a pal says. "He really laid down the law and they had a massive argument."

"He wants her and Harlow in a stable environment with her family close by while he's on tour."

Nicole, however, doesn't see it that way and has accused Joel of abandoning her.