Man... he really chose the worst option... but it's a difficult situation.
She stopped being an idol and is cutting herself a lot. It's not a guarantee, but she most likely started cutting herself to cope with the stress of being an idol, so her idol days are probably not that good of a memory for her. And now he comes and tells her, "You know, I loved your smile when you were in the depths of hell. It saved me." If they had a really close bond, that might have helped her move on, but they haven't known each other all that long, so those words didn't help her at all. And on top of that, he fucking fell asleep after saying his part...
But for him, her smile saved him, and he wanted to tell her that she means a lot to him. He meant no harm, but it still backfired really hard.
And he could have put 1 and 1 = 2 together. She quit being an idol and has a ton of scars due to cutting herself. You can say that that's not enough info, but in topics like that it's better to think 2,3, 10 times about and I prefer to tread lightly. Still, there is no correct answer. Some would prefer you talked directly about the topic, some would prefer to skirt around the topic for a while, before talking about it...
I hope they at least have a decent ending, if not a happy one, but it doesn't seem like that will be the case. She is going deeper and deeper into the hole of depression and despair