WARNING: The following contains major spoilers for Spider-Man: No Way Home, now in theaters.
In the Marvel Cinematic Universe, the world was turned upside-down and back after half of the universe was blipped away for five years and then returned to a world that had seemingly moved on. One of the casualties of this change was Doctor Strange. But unlike the other victims, he knew it had to be done. When he's next seen in Spider-Man: No Way Home, he appears to be coping as best as he can, but some small character moments show he isn't totally the same. With that in mind, one theory explains this peculiarity by stating that Strange is experiencing his own tragedy.
When the first trailer for Spider-Man: No Way Home was released, many speculated that there was something "strange" going on with Doctor Strange. This was mainly because of his blatant disregard for the dangers of a reality-altering spell. However, according to Reddit theorist TheMediocreCritic, Strange isn't acting as he has in the past due to a severe case of Post-Blip Depression. Although his mental trauma isn't clinically diagnosed, some moments show how the changes in his life affect him in ways that seem like coping but are far from it.
In No Way Home, audiences are told that Strange, who was likely in line to become Sorcerer Supreme, was passed over for Wong due to being blipped. Although Wong is equally deserving, Strange made a massive sacrifice to save reality and is also one to struggle with coming in second place. To make this realization even more difficult to deal with, Strange is still trying to shoulder the weight of knowing that to save the world, he had to sentence Tony Stark to die. Unfortunately, knowledge comes with a cost, and Stephen has barely had time to process it.
Because he knows the weight of his choices can't be reversed, it makes even more sense why he was ready to help Peter out when he asked him. Not only was Peter asking him to cast a spell of forgetting for selfless reasons, but Strange knew that if he couldn't help himself, the least he could do was help a kid. That's also likely why Wong gave Strange the greenlight. Casting the spell was partly to help Peter and partly to help Strange find a way to cope with what he's lost by helping someone who didn't deserve his fate.
Although Strange's spell failed the first time, his second casting created massive repercussions for the multiverse. On top of this, he's also dealt the equally difficult blow that the love of his life, Christine Palmer, has moved on since he blipped, as seen in the trailer for Doctor Strange in the Multiverse of Madness. The MCU has emphasized Christine's importance to Strange, and seeing her move on is undoubtedly a tough pill to swallow. So now, Strange has lost his promotion, watched an ally die, cast a spell he can't even remember and lost the love of his life in the five years he wasn't around for.
For Strange, being a hero who knows he has to make the hard choices doesn't mean he's immune to the emotional effects. Upon returning after five years, Strange's life was turned upside down, and his future was taken from him. To try and help others and himself in No Way Home, he casts a spell that ultimately creates even more issues. As a result, the theory that he may be dealing with severe trauma feels likely. But even if it's not the case, it shows just how much Strange has lost to ensure the safety of countless others.
To see Doctor Strange in action, Spider-Man: No Way Home is in theaters now.