My travel plans have changed and it appears that missing my flight home and booking some 1 way trips will be cheaper than changing my flight with American Airlines.

More specifically my wife and I are travelling to Vienna in September and booked the trip months ago. I decided that for my mom's 70th birthday I would take her to Paris. For a couple of really good reasons it would be better for me to just leave Vienna and go straight to Paris instead of coming home for a month and going back to Europe. I called AA and to change my flights and add a new flight home it would cost over $1600. This is on top of the ticket that I already bought. It would be almost $1000 cheaper to fly back to Chicago and then go to Paris the next day. What I want to do is just not fly back with my wife and instead take a $130 flight from Vienna to Paris then a $600 flight from Paris back to Chicago.

The question: Do the airlines really give a shit if I only fly the first half of my trip? The ticket was purchased by my wife can/will they penalize her?

Thanks