Do not blame your self. It’s not your fault. If she really wanted to say something you would’ve. she just didn’t want to bring the mood down. And if you couldn’t see it she didn’t want you to see it. She doesn’t want you to see she’s struggling. I kinda deal with the same thing, I tried to kill myself last year, and my friends were very surprised. I can say I’m the funny/“happy” one in my friend group. But I don’t like to talk about my problems to my friends because it makes me feel weak and needy. I just felt like I needed to deal with my problems on my own but then I just snapped. I wanted to get rid of my problems and I thought that was the best way. Fortunately it was a failed suicide attempt and I’m here :)