As friends of the couple tell Us, Richie, 25, and Madden had circled each other for years, but did not officially meet until mutual friends introduced them at an event in late 2006.

The two started an e-mail friendship – and when Madden split with singer Hilary Duff, 19, Richie made a move.

“Nicole pursued him,� says a source. “She said she liked how he was a ‘good mama’s boy’ in a bad boy body.�

Soon, the pair started going on dates around L.A., including a lunch at the Polo Lounge on December 3. By January, they were an item. After her DUI arrest, Madden asked her to trade her nightlife adventures for nights in.

“Joel tamed her,� says a source close to the couple. “He took her from that dark path she was heading toward and turned her around into a truly responsible person.�