I think that in this case the rule of thirds fails us. May have been better to center them. I agree the road doesn’t continue here, so the people are opposite a compositional void which gives the viewer an “incomplete” feeling, like something’s missing
This is a great use of the sun. The angle here I really like. It's not straight on causing them (her) to squint and it provides a bit of shadow with adds depth.
Above posts make some good points.
Just remember when you take an outdoor portrait, try to eliminate distractions that will compete with attention to the subject. In this case for me the sunglasses, the road and his scarf are just enough that I noticed the people third.
Now onto reflective surfaces. I'm willing to bet if we could see the full rez image, you are also in this picture. Look into his eye...sunglasses. Just another one of those things that is easy to miss when you're focusing on them. Happens to us all, but now you'll be looking for it.
Overall the image is well taken and if the subjects liked it, then it's a win.