I have been watching my mother-in-law regress for years.  She has severe dementia.  She was one of my best friends.  She is not in a hospital - but she doesn't recognize her grandkids - she does still recognize me and her son (but she will think other people are us sometimes) - she is very bored because nothing can really hold her interest - she is very frustrated and sad - she was her high school class valedictorian - superbusy - and always organized - she sees that she is different but doesn't understand it at all.  Right now, we try to keep her as happy as we can - day by day.  I sometimes wonder if keeping her alive is torturing her because as it keeps getting worse and she is less and less able to do daily activities - she is just killing time.  However, we still are able to keep her o.k.  I worry the day will come when we will not be able to do that.
  My mother died of cancer - 29 years ago.  She wasn't diagnosed until stage 4 and she went downhill fast.  About a month before she died she started talking about assisted suicide.  She was definitely not the suicidal type but chemo, radiation (which were all less advanced then), and cancer took their toll.  The last month of her life she was in tremendous pain continuously, she was delirious a lot of it.  My father-in-law died four years ago in similar circumstances - but he was fighting it to the end.
  By the way - I am not sure what kind of Christianity we are talking about but for Catholics (full disclosure - I am not a Catholic - but historically that is what is referenced a lot when you are talking suicides and consecrated grounds) Can Someone Who Committed Suicide be Buried in a Catholic Cemetery?
http://www.holycrosscemeteries.org/faq/index.htm#Section_17 Yes. It is recognized that those who die from the act of suicide deserve understanding and compassion. The deceased may have been suffering from a serious psychological instability, or overwhelming fear and confusion. Therefore, the church offers funeral and burial rites for those who may have died as a result of suicide. The American edition of the Catholic ritual includes prayers for this specific situation. These prayers evoke forgiveness for the departed and consolation to their family.
  I had a close friend when I was in college whose mom committed suicide = not for medical reasons.  I think life is precious and should be supported.  But I also think it is very hard to say you will never do something without being in that situation.  I think we need to provide more help to people in bad circumstances and with mental issues.  But I am not against people making thoughtful end of life choices (perhaps with available counseling to help them make good decisions) because I am not sure I see how forcing someone to live out the last moments of their live in torturous unavoidable delirium and pain is a benefit to anyone.