He never was seduced by the darkside despite many hardships
When one goes back and thinks about what Obi-Wan Kenobi has suffered in his life, it’s truly amazing that he didn’t succumb to his anger and despair and fall to the Dark Side.
Obi-Wan had to sit helplessly as he watched his master get killed by Darth Maul. He was too late to save him and had the only father he’d ever truly known die in his arms. While Obi-Wan bounced back after that stinging blow by defeating Darth Maul, he didn’t let his anger or rage overtake him. He kept his cool and stayed firmly on the light side of the Force.
Years later Obi-Wan would be reunited with the love of his life Satine Kryze the Dutchess of Mandalore. After spending time with her as a young Padawan, he was later reunited with her when Mandalore was accused of helping the Separatists.
After helping her deal with that issue, dealing with Death Watch, and various other conflicts, she ended up dying in his arms after being impaled by the Darksaber that was being wielded by Darth Maul. In her dying breaths, she professed her love for Obi-Wan. That would be enough to send a lesser man into an anger-fueled rage, but again Kenobi showed the strength to overcome his grief and all the negative emotions that go along with it.
Finally, Obi-Wan Kenobi had to face what was basically his little brother in Darth Vader. The young Padawan he taught from a young age, fell to the Dark Side and it was his job to confront and destroy him. Obi-Wan won the battle after failing to talk Anakin to his senses. He couldn’t deliver the fatal blow, instead opting to leave Anakin for dead, after his legless body went up in flames. It’s shocking that witnessing that event and dismembering someone he loved didn’t send him over to the Dark Side. Obi-Wan has the strongest will of any Jedi and his commitment to the Light Side is truly commendable.