The husband of slain Staten Island mom Sarai Sierra posted a cryptic message about infidelity just weeks before his wife left for her fatal trip to Turkey.

“Don’t cheat in relationship [sic],” reads Steven Sierra’s Instagram posting dated Dec. 28. “If you’re unhappy then just leave.”

He put up another message later the same day, adding, “A real relationship is where you can tell each other anything and everything. No secrets, no lies.”

Steven Sierra then took to the online photo-sharing service again the same day his wife departed for her Turkish journey on Jan. 7.

“Good relationship [sic] don’t just happen,” the post reads. “They take time, patience and two people who truly want to be together.”

Five days before Sarai was due back in New York last month, Steven poured out his emotions online again.

“People are to be LOVED. Things are to be USED. The reason why the world is in chaos is because THINGS are being LOVED and PEOPLE are being used,” the message declares.

Sarai was found beaten to death Feb. 3 at the base of ancient city walls in Istanbul 13 days after she vanished.

Turkish newspapers have reported a man, “Tarkan K.,” told police he had sex with the aspiring photographer in a bar bathroom days before she vanished.

Turkish media have also reported that Sarai’s brother, David, warned his sister against cheating on Steven and encouraged her to simply leave him.

Turkish officials have rounded up more than 40 persons of interest in Sarai’s murder but have yet to make any matches with DNA found at the scene.

In an interview with Turkish paper Hürriyet, Steven said that his wife had insisted on going to Turkey and that he accepted her wishes. He has been mum on the rumblings of infidelity.

“I had to permit her to go,” he said. “She was very insistent on going. In such situations. you have to support your wife.”