The couple have been subject to persistent rumours that their marriage is in trouble after Lamar, 33, allegedly cheated on 29-year-old Khloe, with two different women.
However, the real reason behind their marriage crisis is that Khloe believes that her husband has a drug problem, reported TMZ online.
Earlier this week the Kardashian family tried to convince Lamar to return to rehab, but he refused.
Back in 2012, Lamar went to a facility in San Diego, but he was so resistant Khloe hired private investigators to secretly stand guard at the rehab place to make sure he didn't leave.
Also Read
Khloe was convinced of recent reports of Lamar's infidelity, but feels his drug abuse has been the main problem, the website reported.
Neither Khloe nor Lamar has contacted a divorce lawyer.
"Khloe is more concerned about saving Lamar than ending her marriage," the source said.
Khloe and Lamar got married in 2009 about a month after meeting each other.