Request vs. Demand

I just posted in a different thread and ended with the following: 

"I'm not sure why my wife and others seem to think that if I ask it, I am *demanding* it be met *right away* or even *at all.*  That is quite an assumption on her part."

Would somebody please explain to me why what I think is a "request" to do or not do something, which my wife is then free to consider, and choose as an independent free-thinking adult, whether to do or not, is "heard" as a "demand" to do something immediately?  This seems to be an ongoing miscommunication in our household and the source of much strife!

Is it that she does not feel like she has a right to say no?

Is it that she thinks if I request it I must really, really, really want her to do it or I wouldn't request it in the first place?

Is it something in the way I make the request that makes it sound as if I am going to be upset, angry or whatever if she doesn't do it?

Is it a combination of all these things?

I suppose I should just ask her.  But I find that it is hard for me to get an answer from her on something like this.  I think it is just a simple question, and I expect she is likely to read all kinds of things into it and get defensive, etc.

So I am wondering if anyone has a sense of what might be going on and how I might address it.

I must admit I am a rather direct person.  First, I am from New York.  Second, I have learned over time to clearly say what I mean, else risk being misunderstood.  And so maybe my directness is interpreted as being demanding?  But I really expect that my wife, and others, always have a perfect right to say no to whatever I ask.  It doesn't mean that if they say no I won't be disappointed, but they definitely have that right.