he was horrified when he found out that after he used the power of the titan in the port, your family died as one of the consequences of what happened, not counting how much more devastation it brought in its wake.
"you didn't know anything. you had no choice, like my nation once did." you told him that, even though he was sure you should hate him, you had good reasons.
your acquaintance was accidental. a light gust of wind blew the hat off his head when you picked it up among all the passers-by and handed it to him with a smile.
moisture accumulates in his eyes, which he does not notice when he lowers his head, clenching his teeth tightly, realizing that nothing can be fixed.
"I'm sorry, I took away everything you hold most dear. I'm sorry that a monster like me appeared in your life."
"you have nothing to apologize for, Armin."
after these words, he felt even worse, much worse. how can you not hate him after that? even if you don't really hold a grudge against him, Armin will still never be able to forgive himself.
"I don't deserve the opportunity to live, it would have been better if I had—" he cuts himself off in mid-sentence, clutching his head in his hands from hopelessness.