He couldn't bring himself to kill Darth Vader, however, because he continues to associate him with the Anakin he trained as a boy. This is also the exact reason why Obi-Wan didn't kill Anakin on Mustafar despite the opportunity a decade earlier in Star Wars: Episode III - Revenge of the Sith.
In the aftermath of that battle, Skywalker mentioned to Kenobi that he had saved him ten times, but Kenobi corrected him to nine, insisting that what had occurred on Cato Neimoidia did not count.
Obi-Wan knew it was only a matter of time. So, he made the difficult decision to use his learnings and become one with the force, rather than let Vader decapitate him.
First and foremost, Obi-Wan didn't want to have to confront and try to kill Anakin, we see this all the way until their final conflict in their duel where Obi-Wan pleads with Anakin to not make him do what he knows he'll have to do if Anakin tries to attack from the low-ground.
Yes, when Darth Vader turned back to Anakin Skywalker and sacrifice himself to save his son, he dies and Obi-Wan uses the force to connect with Anakin's spirit. In that time Anakin apologizes to Obi-Wan, desperately asking him to forgive him for everything he has done to him and everybody over the years.
He does. Right at the end. With Luke crying over him and Vader sensing his anguish and pain he had inflicted on all those who had cared for him.
It is unclear whether Yoda would be more or less forgiving than Obi-Wan but one thing is certain - the former Grand Master would be ready to treat Anakin as an ally, following the events on the second Death Star. In Star Wars: Revenge of the Sith (2005), Yoda never really lost faith in Anakin in the way Obi-Wan did.
Obi-Wan knew Anakin through and through and understood his overconfidence and arrogance. He knew Anakin would fight with rage and aggression, while he remained cool and calculated. Pairing his understanding of Anakin with his knowledge of Soresu ultimately gave him the upper hand in the battle.
All in all, Anakin felt incredibly betrayed by two of the most important people in his life. We all know he has quite the abandonment issues, and the fact that Obi-Wan and Padmé leave him is likely the primary cause of his extreme hatred.
In Star Wars: Revenge of the Sith, Anakin probably lost his duel to Obi-Wan on Mustafar because he wasn't using a key part of his power. Anakin's lava-filled duel with Obi-Wan Kenobi on Mustafar is one of the best and most consequential duels in all of Star Wars.
Anakin admits to Obi-Wan that he has been arrogant and unappreciative of his training, and apologizes to his master. Obi-Wan assures Anakin that he is proud of him, telling him that he has become a "far greater Jedi than I could ever hope to be."
He couldn't bring himself to kill Darth Vader, however, because he continues to associate him with the Anakin he trained as a boy. This is also the exact reason why Obi-Wan didn't kill Anakin on Mustafar despite the opportunity a decade earlier in Star Wars: Episode III - Revenge of the Sith.
He slays Sidious and returns to Obi-Wan, begging for atonement by execution, only to be met with true forgiveness instead. But just as this fantasy Obi-Wan refuses to strike his former friend down, Vader refuses to turn his back on the dark.
Before he discovered Vader had survived Mustafar, Obi-wan lived with the regret of killing his son, brother and best friend. After, he regretted not killing him and wondered if he had only made things worse by pushing Anakin further into dark side and Palpatine's arms.
After all, SOMEBODY had to train Luke in order to defeat Darth Vader and the rest of the Empire. So how many Jedi died during the attack? Almost 10,000—meaning that only 0.2% of Jedi survived.
In Legends, it was basically all that he did in the early days of the Empire. After his brutal defeat on Mustafar, Vader was fixated on hunting down his former master, and exacting his revenge for the ruin Obi-Wan had made of him.
Originally Answered: Did obi wan and padme have an affair? No, they did not. In the original writing for the prequels, there was talk of making Padme a romantic interest for Obi Wan, so that his conflicts with Anakin would not only be about his interpretation of the Jedi way, but there would be a subtext of jealousy.
This was addressed in Star Wars: The Clone Wars, teasing that Obi-Wan was at the very least suspicious but chose not to confront Anakin. The animated show also revealed Anakin's jealousy over Padmé, foreshadowing his instability and dependence on her love.
Even though Luke tried his best to protect him, Anakin accepted his fate and expressed his love for his son and daughter, Leia, whom he learned about before dying. While it seemed like Anakin had lived a long life, his choices eventually led to his demise at 45.
Obi-Wan was physically struck down in death by Darth Vader in the Original Trilogy. This key moment in the Originals satisfied the question with an answer: in physicality, Obi-Wan may be stronger than Anakin, but Vader is stronger than Obi-Wan.
Obi-Wan Kenobi has provided context for Obi-Wan's failures as a Jedi Master. He failed Anakin by being more of a friend than a mentor. His fears and insecurities held him back, despite having obvious proof that Anakin was a danger to himself.
Anakin Hated Obi-Wan Because of an Imagined Relationship With Padme. Although that couldn't have been further from the truth, Anakin apparently built up a scenario in his mind, which was only heightened by the Jedi Council's obfuscation in other areas.
The canonical comic Star Wars: Darth Vader #7 confirms the younglings' deaths caused Anakin grief, self-loathing, hatred and pain, fueling his descent even further into the dark side.
We go for the more simple answer, further considering the details of the question itself. If Anakin didn't go into that chamber as the Jedi confronted Palpatine, then Mace Windu would have defeated Palpatine, killing him. If you remember, Mace had him. He was ready to kill him.
Master Yoda knew that Darth Vader was once Anakin Skywalker- the boy he sensed too much fear in to train way back in Star Wars: The Phantom Menace.