He's officially moved on from Bachelorette Ali Fedotowsky!

Life & Style can exclusively reveal that Roberto Martinez, 29, has revved up a romance with Playboy playmate Sara Underwood, 29.

"They're serious," an insider tells Life & Style. "He couldn't be happier with Sara."

After getting engaged on The Bachelorette in 2010, Ali and Roberto split in November 2011. But it wasn't over for good. As Life & Style initially reported, the exes reignited their flame while attending Ashley Hebert and J.P. Rosenbaum's nuptials this past December. At the time, a source exclusively said the pair "hooked up after the rehearsal dinner." It now seems, the past is the past.

EXCLUSIVE: Bachelorette Ali Fedotowsky's hot hookup with Roberto Martinez

Now the insider insists Roberto has put everything with Ali behind him. "Sara is nothing like Ali," says the source.

Roberto and Ali didn't get their happily ever after meeting on The Bachelorette, and now Life & Style reports in this week's issue — on stands now — that the future isn't looking too bright for the newest couple of the franchise, Sean Lowe and Catherine Giudici.

EXCLUSIVE: The Bachelor's Sean Lowe and fiancée Catherine Giudici: 2 fights in 2 days

For more inside the Bachelor world's latest relationship drama, pick up the new issue of Life & Style, on stands now!