At the end of Arrian's account of Alexanders life he makes an "apology" of sorts regarding Alexanders mistakes.
He says "And yet of all Kings in the past Alexander is the only one to my knowledge who had the nobility to feel remorse for his mistakes."
Yet, the only instance where I see this is the remorse he feels after murdering Cleitus.
Are there other instances where he shows remorse for his actions?
You need to take what Arrian says with a grain of salt. He is not a very reliable source on Alexander since he writes more than 400 years after Alexander's death. It is the best description we have of his life, but when it comes to feelings and such more abstract things they can be more tricky since Alexander was already a romanticized legend at this time.