DP walks our dog first thing during the week, and I walk him first thing at the weekends so that she can have a lie in. Loosely, on all days after the early morning walk I am responsible for walking him and then DS is responsible for walking him about 4.30pm onwards, however these times are not totally rigid and we all help out depending on who is out and who is at home etc. We don't have a garden so can't just open the back door to let dog out to go to the toilet, we actually have to take him for a walk (though this can be 5 mins long if he's already had enough exercise that day).
This morning I was helping out at a Christmas event at a club I volunteer at. I took the dog for a walk before I left at 8.30am. The event was due to last until 12.30pm but as I was volunteering I was going to be there later than that for clearing up etc afterwards. By the time I got home it was just after 1.30pm.
At 12.25pm DP sent a message on our family group chat to say that our dog was barking to go out and was anyone available to take him out. Clearly I was not at home (she knew where I was) and DS was asleep. I saw the message about 10 mins after she sent it but didn't open or reply to it as I was busy and assumed the people who were at home - DP and DS - could sort it out between them.
DP then sent another message at 1.35pm saying that the dog was going crazy barking. At this point I had just pulled up on our driveway and was going into the house. DP asked me if our dog had done a poo this morning and when I said no, she said "that must be what's wrong with him now then".
At this point I was flabbergasted to realise that nobody had taken the dog out yet. I asked why he hadn't been out yet and DP said, "it's my day off". DS was still asleep (he has issues with insomnia and deep sleep so not unexpected that he hadn't woken up yet). I put the lead on the dog and said to him, "poor puppy". DP said that if that was an attempt to get at her, I was being very rude. AIBU to think that DP was unreasonable not to take our dog out when he needed to, even though it was her 'day off' and she wanted a break? I totally understand her desire for a break, but I think it's cruel to not be flexible enough to take the dog out if there is nobody else around to do it. She didn't know I would be home when I was and DS is unlikely to waken for a while yet. So she effectively left the dog barking indefinitely (it turned out to be 'only' 1 hour 10 mins) because she thought she shouldn't have to take him out today.