Why do the roses on a knockout rose bush wilt so fast? are they suppose to do that for the new roses to bloom?

just bought first rose bush wondering if wilting so fast is normal i only water every 2-3 days.Why do the roses on a knockout rose bush wilt so fast? are they suppose to do that for the new roses to bloom?
Wow, I have 2 bushes and neither wilt that fast. I often take the cut blooms inside to put in vases and they even last a week or so there, too. I do deadhead the bush after it bloom which makes it bloom more, I fertilize them about every 3 months and water them every other day.Why do the roses on a knockout rose bush wilt so fast? are they suppose to do that for the new roses to bloom?
Try watering more often Also, prune the bush after a flower dies