WATCH out, MILA! Your boyfriend has his eye on someone new.

Insiders say that “Two and a Half Men” star Ash­ton Kutcher has struck up a cozy new bromance with British billion­aire Richard Branson.

Ashton, 35, recently put down a whop­ping $250,000 deposit to re­serve a spot on Branson’s Virgin Galactic suborbital spacecraft. And now, the hunky actor and adventuresome en­trepreneur are said to be best buddies.

“YOU should see them in action,” said a source. “It’s a case of the egos have landed as they’ve become their own backslapping boys’ club.

“The two have a lot in common and have even started calling themselves ‘space bros.’ Ashton’s to­tally into it.”

Branson is so taken with the star, he wants to introduce Ashton to his family. He’s also extended an invitation for Ashton to stay at his posh estate on Necker Island in the Caribbean, according to the source.

In return, Ashton has promised to have Branson meet his 29-year-old girl­friend, actress Mila Kunis.

“Mila thinks the bromance is great,” said the source. “She really wants to meet Richard and is even talking about getting her own space ticket.”

And Mila’s not the only one. Branson, 62, says Justin Bieber just signed up for Vir­gin Galactic’s space flight, and it’s been reported that Tom Hanks, Brad Pitt and Angelina Jolie also have spots on the list.

Added the source: “And it goes without saying that Mila is also looking forward to a vacation on Necker Island!”