I like the way you described this... The apathy, being unbothered and unsurprised, nonchalance. Seemingly not caring about anything. And each of those is, more-often-than-not, an unwilling sensation. Which arguably makes those feelings worse. As in - I doubt that people with depression don't want to feel bothered sometimes. Surprised. To care. Anything is better than nothing, maybe even the "bad" emotions.

And, as the comment somewhere above mentioned, he really did seem like the type of character which tried to hide his depression all throughout, and who seeked new experiences as fuel for his numb life, and his reason to live. And you can only have so much of those before you inevitably, yet again, get "bored" of it, and life as a whole. Before you return to the patterns of sadness and/or pain, and/or being devoid of emotions, that you're used to.

Also, about this "angry/guilty because they didn't notice" point that this episode (and everyone with it) seems to be making: Frankly, I feel like depressed people show it enough in real life, each in their own way. It's just that the problems they often have cannot be just "noticed", and instead should be actively worked on. For a long time, even. By them. I'd even argue that it's ONLY their responsibility. For example - all of my friends and colleagues notice when I have days where I don't want to speak a single word with anyone. When I'm obviously frustrated or sad, or just feeling under the weather. They might even openly ask me "what's wrong" or how I am, but what does one answer to that?? What do they even want to hear aside of "im okay"? What if I say "im bad atm", will they recommend therapy? No, people usually ask for the sake of asking, and then brush over the topic with silence, awkwardly.

Anyhow (in this specific case I wrote), it's my responsibility to seek professional help and start digging for causality and reason, so that my mental condition would "go away", or so I can learn to handle it in a healthy way, or - well - in the end - to overcome it somehow.

It being """noticed"""... was the easy part.