Shayne Lamas has reportedly decided to kick The Bachelor: London Calling star Matt Grant to the curb.

Lamas has ended her romantic relationship with Grant after she cheated on him with Las Vegas media mogul Justin Wenerger, The New York Post reported Sunday.

Lamas reportedly traveled to Sin City last Tuesday and hooked up with Wenerger at Blush in the Wynn Las Vegas Resort, according to The Post.

"Matt has no idea," a source told The Post in a Wednesday report. "She hasn't dumped him yet."

Lamas then reportedly spilled the beans to Grant about her rendezvous with Wenerger via a phone call.  In addition, Lamas is planning a trip to see Wenerger "soon" and Grant is "said to be devastated" by the break up, according to The Post.

Grant presented Lamas with his final rose and a marriage proposal -- both of which she accepted -- during The Bachelor: London Calling's pre-taped finale broadcast in May.  

Although they hadn't set a wedding date, Lamas had insisted she and Grant were destined to walk down the aisle together during a post-finale interview with Reality TV World.

"We're madly in love and we're not going to put any pressure on ourselves," Lamas told Reality TV World. "We're in it until the end.  We're engaged and we're going to get married and it's forever."

Speculation that the engaged couple had already called it quits accelerated when he moved out of Lamas' Century City, CA condominium last month, however Grant maintained his stay at Lamas' home was always intended to be "a stop-gap."

Lamas characterized rumors that she and Grant had split as "completely not true" during ABC's The Bachelorette: After the Final Rose special earlier this month.