My bf is late and instead of hurrying, he's relaxing

Hi there, I will go straight into the story: My partner and I were supposed to see each other this afternoon (me coming to his place first). I haven't seen him in a week (which is normal, we're busy during the weekdays). A bit last minute he told me there was a slight change in schedule and had to do something first (I won't give details, but it was a good reason). Along the day he kept me updated and was done in a couple of hours. He then had to go to someone to feed their pet and should have been on his way soon after that. However, he messaged me not too long ago saying he is relaxing in that house (owners aren't there). Now, it is almost 6pm and we were supposed to see each other around 1pm (originally). I feel upset. I got ready a few hours ago and I'm doing small things at home to pass the time. I'm now thinking of telling him that it all took to long and thus decided to study this evening instead. Which means I'm not going to his at all. At the same time, I still want to see him. The fact that he's late because of responsibilities does not matter to me at all. It's the fact he's now lazing around in a hammock somewhere else while I'm sort of waiting and sitting around. That is making me annoyed, frustrated and overall upset. Thus, I am wondering if I should not feel upset and not be petty by saying I won't see him today/tonight at all. What would be the best course of action? Thank you for reading. I appreciate it.

Hi, thank you for your response. He said he felt a little nauseaus so he was resting. What do you mean with that I didn't join him? Join him in what?