Riders was written by Veronica Rossi.
I found this book on a website called Brightly which, first of all, had a list for the most exciting 2016 young adult books (that´s were I found “Riders”) and the design of the website is also the same as the trans pride flag, so I believe that that´s a good website.
The main character, Gideon Blake, wants nothing more than to become a U.S. Army Ranger but then he dies and wakes up as one of the four horsemen of the apocalypse. He and the other three riders meet because of a girl, and she explains to them, that they have to save the world from an ancient evil. They fail, which leaves Gideon to convince the government that the world is in danger.
So this seems to be a book with some (straight)romance which is not my fave but the story sounds really good so we´ll see if I can lay my hands on it.