I've come to breakfast on my own

Absolute non issue.
No one has been rude. They are having in a lie in, you are hungry.
Everyone needs to do what works for them when loose plans have been made.
You are not abandoning anyone, they stoll have each other to chat with and you have to get off.
No need for angst.

My view is they are rude to leave you hanging - its not mega early you only actually started pressing at 10.30 after a number of messages. You are different is all - their plans flexed so yours can to - I wld just text need to get back for pets etc and eat and go.

There were no fixed plans therefore if you decide you need to do what you want to do then do it

Nobody has done anything wrong. You all had a vague plan of breakfast or lunch with the possibility of big lie-ins meaning breakfast was off. You didn't want a lie-in so went to have breakfast.

If you now want to leave before lunch that's fine too but it is a change to the original flexible plan. They be kept to that original flexibility

I'm guessing check out of the hotel is 11am so they'll be up soon. If you need to get back for pets why would you agree to potential lunch?

Pack your stuff up. If they are about you could stay for a drink if they are eating. If not just message and say see you next time, had to get back.

Life becomes a lot easier once you start suiting yourself as much as possible.

You were up and ready for breakfast, you let them know this. They weren't ready to eat at that time so you should have gone ahead and ate.

You are ready to leave now. Just text and let them know this and head off.

No one is being rude. People have different timetables.

They haven’t done anything wrong.
And neither have you.
If i’d been out late, drinking, at a wedding then breakfast before 10:30 was never going to be on my agenda.
You agreed to a plan that possibly included a lunch not a breakfast, indicating that you were happy to wait around for everyone to be up and about.
You’re not, so explain why you need to leave and go home. I wouldn’t meet them now if I was you cos you sound cross with them and might be huffy.

it's fine and most people accept that loose plans aren't set in stone.

Yes, except OP seems annoyed that the friends aren't ready for breakfast according to her timetable, when that was a loose plan from the start. She shouldn't have said she could do lunch when she doesn't want to.

What’s the issue with eating breakfast on your own?

You would be rude to say screw it I am off home just because they have had a lie in.

If they come down and ready to eat then you just have a drink and have a chat. If you don’t want to do that then go home but I think you would come across as petty

Based on you agreeing to lunch if up late, I'd find it a bit weird if you left.

I wouldn't. It's no different to everyone equally agreeing to breakfast and then not making it.

It's an overall plan in theory that was loosely agreed to. The OP could make the breakfast part, the others will be ready for the lunch part. It's fine.

Now, if she were going home in a sulky strop about it, I'd think that were weird but otherwise it's fine and most people accept that loose plans aren't set in stone.

Why did you agree to breakfast or lunch if you knew you couldn’t do lunch because of your pets. You seem desperate to make your friends out to be the bad guys when all they’ve done is sleep in after a long day.

It's a bit weird as you'd agreed to lunch if up late but now they're doing that you're annoyed and questioning motives and saying you need to get back. Go if you need to but don't be aggy with them they've not done anything that wasn't discussed.

This. Not everything has to have a good and a bad guy in it. Is it op that you are self conscious about doing this? Or have not eaten alone before. This is about you not them.

I’d go for breakfast as it’s clear they can’t make it, but would then hang around and have a coffee or lunch and a chat. A late start is normal following a wedding. One’s in the shower so will appear shortly.

The pets complicate things though as it seems you have to head off fairly early. Was lunch ever a real possibility?

Don’t know how to vote as YANBU to go to breakfast, but YABU to be peeved and also to leave early when you were talking about the possibility of having lunch together last night.

Crack on, I’d have been hangry by 10.30. I’d just message saying you’re leaving, stuff to do. It’s not like there’s just one person there, they have each for company plus presumably other guests.

Based on you agreeing to lunch if up late, I'd find it a bit weird if you left. But if you want to get home to your pets, tell your friends that you're going. Next time something like this comes up be clear that you're not staying for lunch, though.

They were a bit thoughtless but to be honest plans change and maybe they needed the sleep or were feeling hungover. I wouldn’t get too upset about it

No.

Just text them and say it was a great day/evening and you're sorry you've missed them but you need to get home and you hope to see them all.soon. or whatever.

It's fine.

Why do you think it might not be..?

I wouldn't even think twice about doing what I wanted in the scenario you've described.

So much angst over a breakfast! I doubt they're giving it any thought, just grab your stuff and head home.

It isn’t rude for you to go but it is t rude for them not to come to breakfast either

This is the problem with "loose plans" someone always interprets them as one way and then gets disappointed when things change.
If you needed/wanted to get home at a certain time to feed your pets etc you should of made that clear when you were making these "loose plans" so your friends were aware.

It's not surprising they didn't get up early after an all day wedding. I dont think they are being rude - but if you need to go home for a particular time thats not rude either just let them know you had to leave.

Nobody is unreasonable. You had loose plans. It turned out you were up before them and hungry. No big deal. It's not rude at all to just head off if you're ready to and are unlikely to want lunch.

I don't think you were BU to go for breakfast without them if you were up and hungry.

They weren't BU though either because it was a loose plan of either breakfast or lunch.
I think if they were good friends that I wanted to spend time with, then I would probably have sat with them while they had lunch and just had a drink or something.

Planned to have breakfast together or lunch if up late.

Would you expect them to think you're rude for having your own reasons for not wanting to hang around or wait until lunch (as you loosely agreed to)?

Leave if you want to but text to say that you need to get back to feed your pets.

Don't you have anyone to feed your pets while you have lunch & a day out with your friends?

You sound difficult op, the plan was for breakfast or lunch- yet you don’t seem happy with a lunch plan after all and are making passive aggressive comments about them preferring it ‘just them’.

if you want to do breakfast because you’re too hungry to wait, then fine. But you are absolutely not allowed to get stroppy with them about not being there for that when that’s why lunch was planned.

Similarly, go home if you need to, but it sounds like you didn’t ’need to’ if you’d woken up later. You’re changing to goalposts to suit your stroppy agenda.