Original source: blog.erikhammar.se
I like it. I think it works because it appears more candid them some of the other post pictures. Although technically, it may not be as sound, it conveys the mood very well. In the end, that is what matters.
If I may make a slight suggestion, if she kisses the horse closer to the front of the mouth, then there will be less shadow on her face, and you can see her lips better.
I agree! Every other image in this post looks posed and not in the least bit natural - despite the attempt by using natural settings. The original image appears as a serendipitous capture of a moment we were all lucky enough to witness. For that reason, I find it to be superior to every other image in this thread - even if it's not technically "flawless" by others' definition. I think it's pretty close to perfect myself.
I'd rather see a true "moment" in the most artificial setting than a completely artificial moment in natural setting.
Regarding the horse in the original image, sure a greater depth of field capturing the horses eyes in perfect clarity would have been great, but as-is works as well as with the horse's eyes closed because it really draws attention to the kiss which is where the actual focus point seems to be which draws even more attention there. Again - a GREAT capture of a beautiful moment.