However, it was implied that he left due to the intense emotional toll of his job, coupled with the stress of his personal life. Here are some clues:
* His family: Stabler's family life was often strained due to the nature of his work. His wife Kathy struggled to cope with the dangers he faced, and their children were also affected.
* His grief: Stabler was deeply affected by the tragic death of his partner, Detective Kathleen "Kate" DiNozzo, in the season 8 episode "Silence of the Lambs".
* His emotional state: Throughout the show, Stabler often displayed signs of emotional exhaustion and burnout, struggling to cope with the trauma he witnessed on the job.
* His impulsive actions: Towards the end of his time on the show, Stabler made some impulsive decisions, including shooting a suspect in the leg, which led to some disciplinary action. This could be seen as a sign of his deteriorating mental state.
The show ultimately chose to write Stabler out, with actor Christopher Meloni choosing to leave the series after season 12. It was left to the viewers to infer the reasons behind his departure.
It's worth noting that Stabler's departure was a significant event for the show, and his absence was felt by both the characters and the viewers.
He returned to the franchise in the "Law & Order: Organized Crime" spin-off, where his backstory and motivations for leaving SVU were further explored.