I let down my brother vs. I let down myself

[shootingstar]

. . .
The book was devided into chapters, chronologically arranged around the years of her life. . .
. . .
There were continual, background regrets, which repeated on multiple pages. 'I regret not staying in The Labyrinths, because I let down my brother.' 'I regret not staying in The Labyrinths, because I let down myself.' 'I regret not doing more for the environment.' 'I regret the time spent on social media.' . . .

(The Midnight Library by Matt Haig, episode The Book of Regrets)

"The Labyrinths" is the name of a band. What do you take "let down my brother" and what do you take "let down myself " to mean? I suspect the meaning of "let down" differs in the two sentences.

 

[jutfrank]

What makes you suspect a difference in meaning? With this context alone, it seems to me this is the normal sense of 'let down', in both cases.

 

[shootingstar]

Then, what is the normal sense of "let down" in this context?

 

[5jj]

let down phrasal verb - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com

Definition of let down phrasal verb in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

www.oxfordlearnersdictionaries.com

 

[shootingstar]

Nevertheless, I don't understand what "let down myself" could mean in this context. Sorry.

 

[PeterCW]

Nevertheless, I don't understand what "let down myself" could mean in this context. Sorry.

Look at the second meaning.

 

[shootingstar]

Could it mean anything like ". . . because I didn't do myself any favours, abandoning The Labyrinths"?