ѕυιcιdє is objectively a mortal sin. Given that it occurs so close to death, by definition, the presumption is that someone who has committed this sin has been lost. So the Church refuses Christian burial for ѕυιcιdєs because the person has died in unrepented public sin, and it would be a scandal to bury such a one. Is it possible that a ѕυιcιdє could be saved? Theoretically yes. It's possible that such a one either 1) received the grace of remorse and perfect contrition before actually passing out of this life in even a split second of time or 2) was not in full command of reason so as to actually commit a mortal sin. But it's unlikely.
One could argue that the kinder, gentler approach would be to comfort everyone with the possibility that such a one might be saved, but, over the centuries, how many souls have been saved because they were afraid of committing ѕυιcιdє due to the Church's teaching? Instead, as a young man I served funerals in the NO for ѕυιcιdєs, and the priest always spoke of how the person was "in a better place now" and "relieved of his suffering". Really? If that's the case, and I really believed this listening, that almost serves as an ENCOURAGEMENT to ѕυιcιdє for someone who's suffering terribly in life. After all, the priest did say that ѕυιcιdє puts one out of suffering and leads to a better place, eh?