Is AUTHOR wrong in the post ? POST : As can be told from the title, I'm married and we have a dog.
He's a long-haired breed and needs to be trimmed regularly, and also a rescue who's been through some trauma. As a result, while he's lovely with us, he's quite difficult when it comes to strangers. After searching, we found a 'dog salon' that specialises in cases like this, but it's quite far from our place- so getting the dog groomed is basically a day-trip.

Now, the last time I got him groomed, when I went to make the next (recent) appointment it turns out their schedule was packed. The only open time anywhere near where I would have wanted turned out to be my wife's birthday (a Saturday). Before making the appointment, I called her and asked if it was okay if I locked that in. She said fine, no problem.

I thought great, all good, we'll do her birthday the day after. I made reservations for dinner on Sunday and considered the matter resolved.

However, come the Friday, she asked me where we were going for birthday dinner tomorrow. I reminded her I was getting the dog groomed on Saturday, and I'd made reservations for the day after instead.

All hell broke loose. She had understood that we'd be going to dinner after I got back from the trimming, She said that unless we celebrated on the actual day, any gestures meant far less, and I loved the dog more than her. 
I had just figured that rather than forcing it after a trek out to the salon and back, starting Sunday fresh would have been more fun for both of us.

AITA here? I was surprised with how upset she got, but I'm pretty clueless in general so I'd like some objectivity.