We finally know what happened to Reus.
According to RN, Reus is suffering from bone inflammation at the pubis. Marco has had trouble with has adductors before. It seems he picked up this injury (or it got worse) during the DFB Pokal finale, but he's been seeking specialist treatment for a while.
This is the same injury that kept Mario Götze out for months. I really hope Marco's isn't as bad.
Marco has posted a statement about it on Facebook.
Reddit user /u/tangled_up_in_blue has very kindly provided a translation:
Since much has been spoken about me in the past few days, I would like to use this opportunity to clarify for you my health status.
Unfortunately I suffered an injury to my adductor during the German Cup Final and it got worse as the game went on. Afterwards I worked for ten days with the German national team doctors to be fit again and to be available for the upcoming Euros. Unfortunately the desired healing process, which would have allowed me to be available for the national team in France, did not work out. Since the doctors did not have a positive outlook for my participation in the Euros, after a discussion with the national team manager, we decided that it is neither in the best interests of the team nor in the best interest of my health for me to travel with the team to France.
The most important thing in these coming weeks is to take care of my injury, with the clear goal of being 100% fit to play for Borussia Dortmund as well as the German National Team.
I would like to explicitly thank the medical team of the German national team for their great support!
I would also like to thank you all for the many "get well soon" wishes and birthday wishes I have received! You give me a lot of strength and mean very much to me!
I wish Joachim Löw and the German team all the best and much success at the Euros in France!
I will be back!
I can't imagine what Marco must be feeling. This is the second major international tournament he'll be missing because of injury. And such a serious injury too!
I hope he's back in time to be our captain next season.
Gute Besserung, Marco!