Why do we put on faces?

I knew she was upset, I knew the situation. Yet, when we piled around our lunch table no one knew anything, or had any idea, because she put on a face. She didn't want anyone to know what feelings she was harboring up inside of her, but why?

1- She was scared
Those around our table will help someone if they know they are hurting. We won't use the occationally seen, "get over it" attitude but will try and help. I knew she was bursting to talk about it, but still she didn't and she joined in the conversation and acted as though nothing was wrong. She was scared we would all think she was being silly, or staying in the past, by her reaction to the situation. None of the rest of us have gone through this and frankly it could easily stay that way for quite some time or possibly we will never have to deal with it. So how could we understand that she wasn't being silly or irrational acting this way? Why would she take the risk of finding out if we understood, if it was easier to put on a face and act happy?

2- Past reactions had told her to stay closed
Unfortunatly when the situation had first arisn, we acted irritated and annoyed that the situation seemed to have such an influence in her life. We would avoid the subject and if it did arise we would give short responses and move on to something different. So why would she put herself out there again if it was going to annoy us? She just wants others to be happy even if that means she has to act as though life couldn't be greater.

3- The situation isn't one to solve so she taken on the motto, "Let bygones be bygones"
The situation she has found herself in isn't one with many solutions, yet it still builds up hundreds of emotions and feelings that one doesn't want to harbor. Yet she has let it be known that these emotions aren't ones of sadness and pain but perhaps conflicting emotions. Yet, with our sad way of acting toward her she has figured that if we are going to be happier and more jovial when she doesn't discuss the situation she should just let it be. The situation will be with her for some time and here we have listened again to know that she is happy right now but still conflicted. Yet, as long as she keeps acting like she has none of these iffy emtions it will be fine.

When we, or anyone else for the matter, see her in the hall, at lunch or anywhere else, we see a broad smile on her face, she is happy. It would be easier to walk with a face of conflicted emotions, but she wants others to be happy and comfortable, that has seemed to make her more happy (as she has commented before) so she will sacrifice "venting" to her friends and will go on with life.