"Grey's Anatomy" lost a pioneer after Justin Chambers announced his departure from the series.

The ABC series reached Season 16 and received an average of 1.3 ratings as its current nine episodes hit 6 million viewers.

In 2018, the program renewed everything and made "Grey's Anatomy" as the current longest-running primetime drama in the history of ABC. The record is expected to continue to expand because of its current season.

Moreover, it started the new decade by grabbing the crown from "ER" for being the longest-running medical drama.

But as it is set to break more records in the future, Chambers will no longer be seen in front of the camera along with the other "Grey's Anatomy" stars -- Ellen Pompeo, Chandra Wilson, James Pickens Jr., Kevin McKidd, Jesse Williams, Caterina Scorsone, Camilla Luddington, Kelly McCreary, Kim Raver and Giacomo Gianniotti.

No Longer Dr. Alex Karev

A source confirmed to Variety that Chambers' final episode on the series was last Nov. 14.

Dr. Alex Karev, Chambers' character, left the Seattle Grace Hospital as he returned home to take care of his mother. After 15 years since he began as a surgical intern at the fictional hospital, Chambers' character became a pediatric surgical fellow.

"There's no good time to say goodbye to a show and character that's defined so much of my life for the past 15 years," Chambers said as reported Variety. "For some time now, however, I have hoped to diversify my acting roles and career choices. And, as I turn 50 and am blessed with my remarkable, supportive wife and five wonderful children, now is that time."

Chambers also took his chance to thank the ABC network, as well as the original cast members of the series before he finally moves on from "Grey's Anatomy." He also acknowledged the past and present cast and staff, as well as his fans for "an extraordinary ride."

While it appeared to be a simple farewell message from Chambers, the actor is battling to protect his mental health.

Real Reason Behind Chambers' Exit

According to Page Six , Chambers is currently receiving treatments for stress and depression before his departure from "Grey's Anatomy."

The 49-year-old actor reportedly checked in to Privé-Swiss, a luxurious facility in Connecticut where they accommodate people and provide their mental health care needs -- particularly "high-functioning individuals" as described on its website.

Selena Gomez and Kit Harrington previously received treatments in the same facility as well.

"Justin was at Privé-Swiss being treated for stress, depression, and life-coaching. There is a lot going on with "Grey's Anatomy" behind-the-scenes right now," a source told Page Six.

The insider did not mention a specific conflict in the series that possibly may have triggered Chambers to leave and focus on receiving mental health treatment.

A representative from Privé-Swiss refused to confirm if the actor checked in since "they do not comment on clients, past or present."

But another source claimed that they spotted the actor near the building of Prive-Swiss and dined with the facility's other guests. The source also noted that Chambers appeared to be thin compared before.

Whatever Justin Chambers feels right now, his fans and "Grey's Anatomy" family only hope the best for him, even if it meant letting him go from the series.

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