AIO about how my boyfriend handled our dog situation?

My boyfriend has been talking about wanting a dog for around six months. I wasn't fully on board because I knew he wouldn't have the time to split responsibilities with me, but he reassured me he will make the time and won't give up on the dog if we get one. So I agreed partly for him. We found a 2 year German Shepherd through a mutual connection. Before we even went to view him, the owner told us over text that he was reactive towards other dogs, so I forwarded this to my boyfriend so he was fully aware. When we went to view him the owner also disclosed he had a torn nail. On the day we saw him, I said let's wait and think about it. My boyfriend insisted we take him that same day.

Worth mentioning.. my dad who is a dog handler had actually originally wanted this exact type of dog for himself, but he told us to go ahead and take him, and that we could see it as a two week trial. If it worked out we could keep him, and if not my dad would take him when he got back from holiday. So there was always a safety net in place.

We split responsibilities fairly so he did mornings, walking and feeding, I handled the rest of the day, lunch, dinner, training and garden play.

I had already arranged to go to Spain for four nights for my dad's birthday (a trip my boyfriend agreed to cover the dog for before I even booked the ticket). When I changed it from three to four nights he used that as a reason to say he's done with the dog and that I should cancel my trip because we are meant to be a team. He gave me a two day ultimatum to get him collected, saying he doesn't want to wait two weeks for "a dog that isn't even his" .. despite this being entirely his idea. Within a week he's completely changed his mind. His reasons are the reactivity, high energy and the nail injury. But ALL of this was known before we brought him home. He knew. I forwarded him the messages.

Also this morning he was cold with me and blamed me for the dog getting water in his ear during garden play, implying I gave him an ear infection (dog is fine now).  He also made a dismissive comment questioning why my stepdad would even celebrate his birthday in Spain??

He then left for work despite saying he'd work from home, and sent me a calm voice note softening his tone shortly after.

The dog is sorted, my family are taking him and a professional handler is going to care for him in the meantime. He'll be absolutely fine.

But I'm left really disappointed. I have actually bonded to the dog now and I'm also stuck on whether to cancel my ticket and wait for my parents to get back the dog.

Am I overreacting or is this as unreasonable as it feels?