The bright blue sky in the first picture is very distracting...it really takes away from the image. Not only is it very bright, but it cuts right through his head. Perhaps a warmer white balance would lessen the distraction, but I just don't think this picture will ever be great.
Number 2 is very nicely done. Good exposure, and a nice job of rim-lighting her hair and keeping the sun/shadows off of their faces as opposed to #1. This is definitely my favorite of the 3.
Number 3 is pretty nice, but I don't love it, although honestly I'm not quite sure why! It looks too in-between as far as contrast. I would either add contrast, or lessen the contrast and saturation if that's the type of look you are going for. I think having them centered between the trees would have been advantageous in this picture. Having them dead center with the trees off-center just bothers my head a little bit!