The question that begs to be asked is: Why? Followed by an immediate: And who says? I imagine the answer to the first is "shidduchim" (matchmaking); I am unsure of the answer to the second. Has the family consulted with a prominent Torah authority who ruled they must keep the illness a secret? It seems absolutely impossible to me that such a ruling would be handed down; for two reasons. Firstly, Klal Yisrael (The Nation of Israel) is characterized by three inborn traits, inherited from our forefather, Avraham Avinu: rachmanim (merciful people), bayshanim (modest people), and gomlei chassadim (people who bestow goodness and acts of kindness upon others). We are taught, for example, that the reason Hashem has struck some of our nation with the challenge of poverty is to enable the rest of us to snatch the privilege of helping our brethren. Wouldn't the same apply to a physical challenge, such as cystic fibrosis? Wouldn't the community want the privilege of rising to the challenge, helping the family and this young woman through their difficult trial? Entire organizations are ready and waiting to help the chronically ill; why deprive them of the opportunity?
Secondly, hiding an illness of this sort implies something shameful about it, which is antithetical to Jewish thought which believes that everything comes from G-d. This young woman was given the challenge of cystic fibrosis the way some people are given the challenge of arthritis, or jealousy, or wayward children. Where does the need to hide come from?
Thirdly, here is a young woman who is suffering unimaginably, physically and emotionally. Doesn't she deserve, at the very least, the support of her friends and family? Why exacerbate her suffering by making her undergo her nightmare in complete and total isolation--actually, in something much worse than isolation: in a total, fabricated, charade? We know that "a sorrow shared is a sorrow halved". Why should this young woman be an island? Why should her family be tormented alone? Why would it even be permissible to increase her suffering through this modus operandi? It is really quite beyond me to understand.
If it is shidduchim the family is concerned about, and if that is the root cause of making their decision to hide their daughter's illness, that would raise a very, very thorny issue, one that we, as a society, have long evaded. That's for another post--probably juicy, possibly of a personal nature. Meanwhile, I cannot judge this particular family, and I imagine their decision was absolutely heart-breaking. All I can say is that my heart goes out to them and their poor daughter. May she be granted a refuah shelaimah (complete recovery) very soon.