Small Example of Big Frustration

I fell like it is so hard to have even the simplest conversations with my wife, and it has become so frustrating. 

An example from last night:

Me, as we are about to watch a recorded TV show:  One more show and then bed?

Her, referring to the fact that it's a little earlier than our usual bedtime:  Oh good.  I can go in early tomorrow.

Me, wondering what time she will be getting up in the morning:  Oh, what time do you need to leave?

Her:  I don't need to leave at any time.

Me, thinking she must have misunderstood my question:  Oh, let me rephrase the question - what time are you planning to leave?

Her:  I don't know.

Me, still attempting to find out what time she is thinking of leaving in the morning:  What time are you thinking about leaving?

Her:  I'm not thinking about any particular time.

Me:  About what time are you thinking of leaving?

Her:  I don't know.

Me, starting to get frustrated that what I thought was a simple question, i.e. what time are you leaving tomorrow, is not getting answered:  You mentioned something about leaving early tomorrow when I mentioned going to bed.  I'm just trying to figure out what time you are planning on leaving.

Her:  I don't KNOW!

Me:  Why do you have to make everything so difficult?  I just asked a simple question!

Her:  I'm not trying to be difficult.

Me:  Then why won't you answer my question?

I never did get an answer.

I can't tell you how common interactions like this are.  It's become so difficult just to have a simple conversation with my wife.  I end up getting frustrated, and I know she does too.

And so, it's rare to have conversations that are pleasant.  One more thing I used to enjoy with my wife that I don't anymore.  It's getting so that I avoid talking to her unless absolutely necessary.

Any thoughts, suggestions?