The soft, muted colors are really nice as is the composition.
It makes me want to be there and go out with them....
My understanding of the Rule of Thirds calls for the subject to be placed at least approximately where the horizontal and vertical lines that are one-third away from the edge of the frame intersect. In this case, the subjects are placed horizontally almost exactly in the middle. None of that detracts from your very nice image; I'm just making an observation that it doesn't seem to be an example of using the Rule of Thirds.