I didn't use any layers to alter the colors, and Elena is lit by the exact same light sources as the background. What you're seeing, is a combination of the low direct sunlight during sunset that's back-lighting the scene from behind, warming up the background (including shining through the the semi-translucent leaves), and her front being lit only by the sky dome (which is sunlight that's bounced off the atmosphere in the sky and then back down as a soft, diffused light, which is cooler due to how the atmosphere absorbs and scatters specific colors frequencies, contributing to the blue sky phenomenon).
I'm a Lightroom user, and when I do RAW processing in it, if I don't like the white balance, I simply choose among the white balancing preset options to see if any of them are more pleasing, and if not, I choose the closest one to ideal and then tweak the temperature setting a bit (usually I move the slider towards magenta--around +10 ~20--since I dislike the yellowish color casts that's very common). I also have custom camera calibration profiles I created for each of my cameras, getting rid of too much yellow and adding a bit more magenta/red. The profiles are applied by default during imports.
On a related note, is that I come from a classical artist background (drawing/painting), so my mentality is a bit different from most photographers. It seems if you read enough photography/camera forums, most photogs tend to be stickers for accurate white balance, tack-sharp details, everything in focus, etc. I don't subscribe to any of that. I think leaving an artistic footprint/fingerprint behind in your work is a good thing, and unless you are shooting photojournalism or anything else that requires strict realism/accuracy/detail, it's perfectly fine to go for a more distinct color cast (when appropriate), or have selective detail (shallow DOF), not have insanely sharp details that, etc. In fact, I love impressionist paintings (particularly painters like John Singer Sargent, Joaquin Sorolla, Anders Zorn, Richard Schmid, Pino Daeni, etc.), and I think when photos veer a bit towards that aesthetic sensibility, it's not necessarily a bad thing (although many photogs would likely criticize photos like that--especially on a forum like DPReview).
Thank you for the explanation Lunatique. I'll play around with the white balance and sliders a bit. I like warm colors. And I understand what you're saying in your last paragraph. I pretty much agree with it all. Follow your own rules. BTW, love your work with your beautiful wife. I love using my wife as a model but she doesn't have the patience to be a model. No time for camera adjustments with her!