If you love the trees and flowers, why are you hurting them? Plants grown inside the house are actually wonderful for your health because they naturally filter the air and replenish oxygen.
When someone gives me cut flowers, I give them plenty of sunshine, spring water not tap and a shiny penny in the bottom of the vase. In the cold weather months it's harder to keep them fresh when you heat your home. Try to keep them in a cooler room away from air vents or radiators.