Pressure to grow hair long?

My wife wears her hair very short by most peoples' standards.  It's not a buzzcut or flat-top or anything like that but it is very short.  She likes the back clipper-cut and has the sides cut above her ears.  The top is a few inches long. 

 

I've cut her hair since before we were married.  She asks me to cut it every 3 weeks, on average.  Her style is modeled after a photo she found in a catalog years ago.  She had longer hair back then but wanted something new.  The look is not very contemporary, in my opinion.  It was a pretty trendy look when she originally selected the cut.

 

I've told her how I feel and suggested she wear it a bit longer but I would never consider asking her to grow it long enough to even touch her shoulders.  I know that would never happen.

 

A few months ago, since she seemed dis-inclined to grow her hair, I stopped cutting the back with the clipper.  Instead, I used scissor-over-comb to cut the back.  Gradually, it got a little longer and I thought it looked more stylish.  Not long after this "transformation", however, she asked me to be sure to use the clipper because I wasn't cutting it short enough.  She said she likes the way it looks and feels better when I use the clipper.

 

Just as any other stylist, I need to tread carefully when suggesting style changes for my client.  This becomes even more sensitive when the client is my wife.