The 35-year-old rocker inked his new wife's name across his chest (above a tattoo of a heart), sharing a pic of the body art on Instagram Monday.
"Thinking bout you #LuckyMan," he wrote.
The couple have been the picture of domesticity since tying the knot in an intimate ceremony on Jan. 5. They've been spotted enjoying basketball games together, shopping for groceries at Whole Foods and going on double dates with Madden's twin brother, Joel, and his wife, Nicole Richie.
"She seemed excited to be celebrating her first Valentine's Day with Benji," a source told PEOPLE of the date. "They had a fun, three-hour dinner with Nicole and her husband."
Insiders say they've never seen Diaz, 42, so happy. "Since she started dating Benji, Cameron has changed in a very positive way. She can't stop smiling and seems much happier," another source previously told PEOPLE.