My employer broke a promise on a personal issue. Upon applying I mentioned I would like to introduce a dog to the office. They liked the idea and in the following months we talked about it a couple of times. (It would be a diabetes assist dog, which was the only reason they were OK with it, but based on my emotional involvement this is not necessarily important for the question as I realised after a comment).
I moved because my landlord in my old flat wouldn't allow dogs. We talked to all other employees and during the talk they seemed OK with it. I started to make the flat dog safe, I searched for a trainer, prepared a lot and started looking for a suitable dog.
Now, after telling my employer for several weeks that I'm actively looking for a dog and being in the proceedings of adopting one, they talked to me and said they changed their decision. The reasons are understandable and fair, it concerns other employees and their health. In other words, my right to bring a dog is gone. This means I can't adopt the dog because then it would be alone for 8h a day.
Understandably I am quite sad and had a hell of a night. All that I've prepared is useless now and the emotional involvement I already had doesn't help. My question is, how much of this should my employer see? Is it more professional to put makeup on, get smiling and proceed like nothing happened? I am quite hurt and I am not sure if they should believe everything is just fine, on the other hand it's only partly their fault. I would be glad for any tips about how to appear and maybe how to cope with it professionally.
We are a small company with about 20 employees and I am on good terms with the owner. We see each other daily.