Ashley Greene and Joe Jonas Split

By Tim Nudd

03/17/2011 at 11:10 AM EDT

It's twilight for Ashley Greene and Joe Jonas's romance.

The couple, who had been dating since last summer, have broken up, their reps confirm to PEOPLE.

Greene, 24, who plays Alice Cullen in the Twilight films, and Jonas, 21, one-third of the Jonas Brothers, went public with their relationship last fall after dating quietly for a few months.

PHOTOS: Ashley Greene & Joe Jonas: The Way They Were

A source told PEOPLE at the time that Jonas was "head over heels" for Greene. They remained an item through the winter, most recently celebrating Greene's 24th birthday last month in Las Vegas.

In recent weeks, the two, who were never shy about affectionate public appearances, were spotted – separately – at various L.A. clubs. On March 11, Greene and Zac Efron partied with pals at Trousdale Lounge, while Jonas spent a guys' night out at the same club three nights earlier.

Greene is currently filming the latest Twilight film, Breaking Dawn, in Vancouver. Jonas, who previously dated Demi Lovato and Taylor Swift, will release his first solo album this summer.

• Reporting by JULIE JORDAN