Be there for her whenever you can. Tell your friend that if something's going on, she can always talk to you. She might talk to you about it, and she might not. But it lets someone know you care about them when you tell them you're always there for them.
That's what my taekwondo instructor did for me. Not too long ago I was really anxious, really scared all the time, and I was never happy. But I never really talked to him about it, except for one time when one of my family members asked him if he ever worried about his future when he was growing up. I realized immediately that they had asked that question for me, because they knew that I would never talk to him about it. It wasn't that I didn't like him; he's awesome. It's just that I was really, really shy and I was awful at talking about my emotions.
. . . come to think of it, it was a few instructors, actually. They changed everything, and having them in my life really made a difference.
I was helping out at the Halloween event, and there was an instructor there who I hadn't seen in FOREVER. He asked me how school was going, like he always did, and this time, instead of saying "Okay", I actually told him the truth, how horrible it was, how I cried almost every day. He gave me some advice on how to deal with it - advice which I sadly don't remember. (I'M SORRY SIR YOU HELPED ME A LOT BUT I FORGOT WHAT YOU SAID I'M SO SORRY D:) He said it was bad advice, but it was actually really good advice. I don't remember what it was, but I do remember that it helped me a lot.
When I told him about school, my instructor (the one who's usually there) must have overheard. He didn't say anything, but he was listening. He must have been, because of what happened next.
One day he noticed I was complaining a lot, a lot more than usual, and I kept telling this one kid to stop bothering me (they wouldn't. XD). I was always telling them that, but this time maybe my instructor could tell that today I REALLY wasn't okay with being bothered. Like I wanted to be left alone for some reason. After class he said, "Hey, if something's going on, just let me know."
Then one day we had a different instructor, who I saw maybe twice before but didn't know very well, and I was super anxious that day. I was afraid of him for some reason, despite knowing how nice he was, and he picked that up really fast. But it came across as a boiling mixture of sadness and anger, and I hardly talked AT ALL, so then he was scared of ME. (Because my instructor probably told him I was really nice and really talkative, because that's how I usually am at TKD.) I still feel really bad about it, because it was my problem and I should have controlled my fear better. But despite being intimidated by me, this instructor actually spent time with me. There was an odd number of students in the class, so there would be one person without a partner when we paired up. The instructor chose the groups, and he put me by myself . . . but that was because HE was the person I was working with. That happened almost every time. Throughout the entire class, he was really encouraging, and everything he said empowered me. At the end of class, I was back to normal again, laughing and saying sarcastic things to my classmates (not in a rude way; we're sarcastic when speaking to each other, but we're still respectful).
The next class, I learned from my instructor that the other instructor was actually intimidated by me. (I didn't know this before.) Upon hearing this, I felt really bad and went into Sad Mode. This happened:
Me: -looking at floor- :(
Instructor: Kyorugi, look here. :)
Instructor: SMILE :D
Me: -hides face in hands- -smiling- NO
Instructor: LOOK AT THIS FACE :D
Me: -laughing- NO
Instructor (to classmate): She knows she's going to smile if she looks up. :)
It still bothers me to this day that I didn't look at him. I will die not knowing what face he was making at me. XD
So then, later, during kicking practice (I was working with my instructor):
Instructor: [other instructor's name] was intimidated by you.
Me: Yeah . . .
Instructor: He said you seemed really angry and sad.
Me: Yeah . . . um . . . I . . .
It was then that I realized I had to talk to him about what was going on. So I did; I asked him for advice on being happier (because he already figured out that I was angry, sad, and scared all the time, because the other instructor told him and to be honest, my instructor could probably tell. He's really good at reading my emotions). He said a lot of stuff - he emphasized craziness (the good kind) the most - and what he said really helped me. He also surprised me by saying, "I feel a lot of the same emotions you do. Like, 'I don't want to talk to anybody . . .'" But yeah, what he said made me feel a lot better. Ever since then, I've been a lot happier and hardly anxious at all.
Later in the semester my instructor was sick, so we had the other instructor again. I was really nervous - not anxious, though - because I thought he was mad at me, but he wasn't. When I entered the dojang he said, "Hello, Kyorugi! Long time no see." Yes. He remembered my name! :D This class went a lot better and after class, instead of bowing to me like everyone else, he high-fived me and said, "Great job! :D" He was there the next class too, and the same thing happened. It wasn't that he was ignoring everyone else, it's that he . . . he gave me a second chance. He knew what was going on, and he understood. I never talked to him about it, but he helped me a lot just by being there.
I wish I had the courage to actually say this to you, but . . . thank you. Gamsahamnida. Thank you for everything. All three of you. I'm awful at talking about my emotions, but please know . . . please know that you made a difference. You made everything better and now, thanks to all of you, there's nothing holding me back from achieving my goals.