is it rude?

Im trying to sel a bedroom set on marketplace, I had someone interested first, but only for a part of it, and said maybe the rest will fecide when she comes, shes not sure if she can move herself etc, I had another buyer interested today, wants the entire set for sure can come pick up now, and has a way to move themselves and everything, the second option seems a lot easier and a smoother sale than first but the first lady was 1st & told me to hold it till hse gets paid the end of week…

What would you do?

I really just wanna go ahead and sale to second person but i dont want to be unfaithful or rude.