WHAT COULD HAVE BEEN A MASTERPIECE

Wtf is that ending????Why??I mean it was great in the beginning what went so wrong
It just kept becoming worse and worse I mean why it could have succeeded but they just had to ruin things like no of the couples really ended up together???am so confused but overall it was okay I watched ep 1 to 24 without problem then it went down ? hill things got messy Why did he have to die? Why didshe have to become young again??Did the othersgettheir happy ending in that world?? Did the second sister end up with her lover at the end??soooo many questions