'Flip or Flop' Star Tarek El Moussa Cleans, then Sells Houses ... Alone

"Flip or Flop" star Tarek El Moussa's the only pretty mug you'll see on the flyer pimping his real estate biz ... Christina's apparently been kicked to the curb.

TMZ got its webbed hands on Tarek's ad that started circulating in the O.C. ... and he's flying solo. Tarek's now with Sotheby's ... and she's clearly not.

It's a big departure from they way they created their brand ... sort of like Sonny and Cher.

Tarek and Christina are putting on happy faces while they film their TV show ..but off-screen it's now The Sonny Show.