BIG SPOILERS AHEAD
"I'm pretty sure Lysadra or Xander can die at the end depending on how friendly their relationship is - in my case Lysandra wanted to do it, but Xander decided to intervene, and in the end both survived (wich I guess is the key for his good ending, by the way)." - You obviously guessed correctly, :)
"On a side note, is it possible for people to die in the game?" - There's plenty of times someone can die - it's actually pretty hard NOT to let people die in this game :)
In chapter 11:
- MC can be killed by Alexia out of jealousy;
- Alexia can be killed by Xander;
- Xander can be killed (poisoned) by MC;
In chapter 12:
- MC can be killed by Valedorn;
In chapter 14:
- Alexia can be killed by MC;
In chapter 15:
- everyone (including MC) can be killed by Master Altrane;
- Osario can be killed by Master Altrane;
- Arantis can be killed by Xander;
- MC can be killed by Arantis when Master Altrane controls him;
In chapter 16:
- MC can die (sacrifice herself);
- Xander can die (sacrifice himself);
- MC can kill everyone (bad ending nr 2);
- MC and Xander can together kill everyone (bad ending nr 3);
- Xander can kill himself and MC trying to stop her (ending nr 6);
- MC can have her memories wiped out again (bad ending nr 4).
Kudos to you if everyone survived in your playthrough! :)