Here it is - list of possible endings and simplified requirements for getting them:
ENDING NR 1 (BAD): LIFE IS NOT A FAIRY TALE – MC has to die before reaching the final chapter of the game
ENDING NR 2 (BAD): QUEEN OF DARKNESS – MC has to fail her character's test (don't be a good enough person); MC can't be in relationship with Xander
ENDING NR 3 (BAD): WORLD IS OUR PLAYGROUNG – MC has to fail her character's test, Xander has to fail his character's test, MC must be in relationship with Xander
ENDING NR 4 (BAD): HISTORY IS WRITTEN BY THE VICTORS - MC has to pass her character's test, Xander has to fail his character's test, MC can't choose to sacrifice herself for others
ENDING NR 5 (NORMAL): ULTIMATE SACRIFICE - MC has to pass her character's test, MC can't be in relationship with Xander, MC must choose to sacrifice herself for others, Xander has to fail his character's test (or he can pass it but only if MC wasn't too nice for Xander)
ENDING NR 6 (NORMAL): TILL DEATH DO US PART - MC has to fail her character's test, Xander has to pass his character's test, MC must be in relationship with Xander
ENDING NR 7 (NORMAL): LONE SHE WOLF – MC has to pass her character's test, Xander has to pass his character's test, MC can't be in relationship with anyone or MC was in relationship with someone who died
ENDING NR 8 (GOOD): GOLDEN AGE – MC has to pass her character's test, Xander has to pass his character's test, MC must be in relationship with Casimir, MC can choose to sacrifice herself for others only if she was nice for Xander
ENDING NR 9 (GOOD): NEW BEGINNING - MC has to pass her character's test, Xander has to pass his character's test, MC must be in relationship with Arantis, Arantis must survive the final fight, MC can choose to sacrifice herself for others only if she was nice for Xander
ENDING NR 10 (GOOD): BETTER WORLD - MC has to pass her character's test, Xander has to pass his character's test, MC must be in relationship with Osario, Osario must survive the final fight, MC can choose to sacrifice herself for others only if she was nice for Xander
ENDING NR 11 (GOOD): TWO AGAINST THE WORLD - MC has to pass her character's test, Xander has to pass his character's test, MC must be in relationship with Xander, MC must choose to sacrifice herself for others
Getting all of them won't be an easy task! :)