Joe Manganiello "Very Happy" for Costar Alex Pettyfer's Engagement

Credit:; Jeffrey Mayer/

As Us Weekly exclusively reported on March 13, British bad boy Alex Pettyfer is engaged to Elvis Presley's granddaughter Riley Keough -- and no one is more excited about their wedding news than their Magic Mike costar Joe Manganiello.

"If that's true, then I'm very happy for them," Manganiello, 35, tells E! News. "I love them both."

Though multiple insiders confirmed Pettyfer, 21, and Keough, 22, are indeed engaged, neither stars' reps responded to request for comment. Manganiello, however, said that given their chemistry on set, he saw Pettyfer's proposal coming from a mile away. "I think we all did," he explained.

An insider echoes what Manganiello noticed between the stars, telling Us: "They have been inseparable since they started dating."

The raucous Magic Mike -- which features Matthew McConaughey and Channing Tatum as male strippers -- has even inspired a naughty "bachelorette party" idea for Keough.

"Maybe we'll all take turns giving Riley lap dances," Manganiello joked to E! News, adding that they've all grown accustomed to wearing G-strings. "Maybe we can just call the costume department and bust them back out."

Prior to their engagement, Pettyfer dated actresses Emma Roberts and Dianna Agron. Keough was linked to Ryan Cabrera and Jonah Hill.