Khloe Kardashian and Lamar Odom's marriage problems include "hardcore" drug abuse reportedly.

Odom has had a long-term "hardcore" recreational drug problem that has turned "dire" following a recent unsuccessful attempt at an intervention, TMZ reported Friday, citing multiple sources familiar with the former Khloe & Lamar stars' situation.

According TMZ, Odom has had a drug problem for two years -- leaving Kardashian to deal with "a double whammy" which has also included multiple allegations that her husband of four years has cheated on her.

The Keeping Up with the Kardashians star reportedly convinced Odom to go to a San Diego rehab facility last August, however Odom threatened to leave "constantly" before leaving the facility for good after only three weeks.

Kardashian was allegedly so concerned Odom, who currently plays for the Los Angeles Clippers, would remain in the rehab facility that she secretly hired private investigators to monitor him while he was there.

Odom reportedly managed to stay clean after he left the facility but "slipped deep back into hardcore recreational drugs" after the Clippers' NBA basketball season ended this spring -- resulting in the entire Kardashians clan attempting to stage an invention and convince Odom to re-enter rehab earlier this week.

Odom reportedly rejected the request that he return to rehab, however, causing Kardashian to throw him out of the couple's house Wednesday morning (a departure that was captured in paparazzi photos which showed Odom and a friend loading his car with luggage).

While rumors that Kardashian will be filing for divorce have circulated for months, she is reportedly currently primarily focused on Odom's well-being.

"Khloe is more concerned about saving Lamar than ending her marriage," a source told TMZ, which also reported neither party has contacted a divorce lawyer yet.

On Thursday, Kardashian -- who reportedly hasn't been seen in public with Odom since June 2 -- was spotted leaving a Los Angeles gym looking distressed and not wearing her wedding rings, which she normally wears regularly.

The sighting also followed multiple recent reports that Odom has cheated on Kardashian numerous times during their marriage -- one of which was an alleged extensive affair that lasted for about a year.