Mauricio Umansky Blames 'Dancing With The Stars' Mess-up On 'RHOBH' Trailer

Mauricio Umansky says his "DWTS" mishaps last week were a direct result of the "RHOBH" trailer, which dug deep into his marriage with Kyle Richards ... and dropped right before he put on his dancin' shoes.

Mauricio opened up about the flubbed steps on Tuesday night's episode ... telling his dance partner, Emma Slater, he blacked out on the moves last week because the trailer unnerved him.

The trailer digs into his marriage, with several of Kyle's costars even raising issues of infidelity  ... something he and Kyle call B.S.

Mauricio says he felt additional pressure because his kids were in the audience... so it all kinda came tumbling down on the dance floor.

Fans of the show know he tried improvising his Salsa routine about halfway through, forgetting the moves and ending up with a 12 out of 30 -- the lowest score of the night.

Still, they didn't get the boot despite the rough Salsa ... the door was shown to Jamie Lynn Spears, instead.