PK Kemsley isn't looking back at his marriage to Dorit ... cause TMZ has learned he's jumped into a hot new relationship roughly a year after Dorit filed for divorce.

Sources close to the couple tell TMZ … PK has moved on after the filing, and he's seeing a woman named Tatiana Kharchylava -- a London-based creative executive who's built a strong reputation in elite circles -- who he met through Boy George last year in England's capital during an art collab and sparks followed.

While PK's still based in Los Angeles, our sources say he's making regular trips across the pond to see her ... essentially splitting time between La La Land and The Big Smoke.

And, Tatiana's happy to come to L.A., too ... with our sources telling us the two were spotted Tuesday night dining at Mr. Chow's in Beverly Hills with the owner's daughter, China.

PK has kept quiet about his estrangement from Dorit ... but, we're told he's hurt by her portrayal of their relationship on "The Real Housewives of Beverly Hills" last season.

Our sources say he doesn't plan to spar with his estranged wife in public -- for the sake of the kiddos -- but he believes the truth about the split will eventually come to light.

Dorit filed to divorce PK last year ... and, it hasn't been the most amicable split. The two are locked in a custody battle, and Dorit even said publicly PK hasn't tried to see their kids-- an assertion he vehemently denied.

Bottom line ... PK's embracing new love -- while still battling his old flame!