Six months after tying the knot, Benji Madden is still head over heels for his wife, actress Cameron Diaz. The rocker wished Diaz a happy birthday in the sweetest Instagram post, reported Entertainment Tonight.

"Happy Birthday to my Beautiful Wife," wrote Madden, 36, in the Instagram caption of the couple's ussie, adding in relevant emojis. "My best friend and Everything else- there's so much I could write. I'm the luckiest guy alive- I get to spend the rest of my life right here. I love this Woman!! Many more Baby!!"

Madden posted the photo on Diaz's 43rd birthday, which was Aug. 30, according to E! News. The couple spent her birthday together in Australia where Madden is filming the Aussie version of "The Voice" in which he's a judge.

The couple, who got married in January, has not lost the newlywed glow, reported People. They're constantly being photographed together, showing off major PDA on dinner dates and sporting events.

It's speculated that they hope to make an addition to their family soon, according to People.

"[Cameron] will take things as they come," a source told People. "But don't be surprised to see her calm down a bit and get in the best shape for a possible pregnancy."

See Madden's sweet birthday message to Diaz below.