James Harden fears Khloe Kardashian is still carrying a torch for ex-husband Lamar Odom and speculation is growing it could be the only reason the NBA star hasn't proposed to her.

HollywoodLife reports the 26-year-old Houston Rockets All-Star guard wants to take things to the next level, but is hesitant because Odom remains a much bigger part of his reality TV girlfriend's life than he could ever be comfortable with.

"James is still not certain that Khloe's over Lamar, and it drives him crazy," said a source. "He found it odd that they both sat on their divorce for more than a year. It's like they were giving each other more and more time to get back together. That scares James and is still on the back of his mind."

Thirty-two-year-old Kardashian was married to Odom for more than four years before filing for divorce in late 2013 amid widespread rumors of his infidelity and growing drug use. Still, it was more than a year later before Kardashian made moves to finalize the split.

The source adds Harden has now also grown tired of seeing all Odom's "s*** at Khloe's house and in her garage." All the little reminders of the former NBA Sixth Man of the Year award winner have left Harden wondering if he and Kardashian are truly on the same page.

In a newly released clip of an upcoming episode of her "Keeping Up With The Kardashians" reality show, Khloe freaks out over misplacing her Blackberry because it's the only phone she has with Odom's number, prompting sister Kim to chastise her over her lingering attachment to her ex.

"Lamar and I loved each other deeply and I don't believe in just acting like that relationship never existed," Khloe later responds. "Things happened but that doesn't just stop me from caring about him or loving him, so if I feel the need to check on Lamar, that's my prerogative and I'm going to do it."