There is no linear relationship between the dollar and the markets. Right now (recently) they care, but a year ago they cared about something else.
The traders are always looking for something to focus on, be it oil, interest rates, earnings etc. Its a never ending roller coaster of what matters most. Just when you think you have it down, it is already shifting to something else.
Play it for what it is short term, but realize that relationships (correlations) come and go like the wind.