Dying flower

I kept a fake flower at my work space when i study so i can look at 'greenery.' I don't want to keep a real one because it's a hassle. Plus, it should be where it belongs-with nature, out in the park etc.

Anyways, my sister brought home what i believe is a chrysanthemum (not sure if i spelled that out right) flower. She took out my fake flower and replaced it with that. I was a little angry because she did not ask for my permission and told her that she should be the one to change the water. (she never does it)

It has been like 5 or 6 days now and i think it's dying faster than it should be. We're not really good at taking care of plants... (That's one of the reason why i have or had a fake one on my desk)