My money would be on unadulterated ambient light. Once you learn to decompose studio light, you see it everywhere in natural images, however it is possible to overanalyse.
Late evening sun gives you the highlights you see in addition to filling in the shadows light a softbox. It may be the case her face was lightened in PP. It also gives you the same bokeh as this image when shining through trees.
If there were softboxes left and right you'd see their specular reflections in her glasses and eyes. In particular I would expect a strong white line where her eyeglass lenses curve at the extremes. The reflections could have been photoshopped out, but there are still some reflections in her eyes which looks like light coming through trees which makes you wonder why those would have been left in. Finally if I were shooting a model with glasses in the golden hour I certainly wouldn't introduce any extra lighting as that's simply more work all round!
I've shot in similar conditions with similar results. I'll see if I can dig out some images. Edit: here's an image with strong highlights and softly lit faces, no extrnal lighting:

Finally, where did this image come from? Could you ask the photographer how it was shot?