Imagine if you will that you run an office. Not just any office, but a very important one. One that will cease to function at all if it's left alone for more time than it takes to go to the bathroom. (And not one of those cozy, read a book bathroom breaks some of you are fond of. I'm talking just a quick in and out, take care of business bathroom break.) It is so important that someone is in the office, in fact, that if it is left alone the law will come along and throw you in jail if you leave it unattended.
Now lets pretend that you are in charge of this office all by your little self from 8:00 am to about 5:30 pm. Now before you get your hopes up, you don't get to leave at 5:30 - oh no. At 5:30 you get someone to come in and help you with the office. This relieves some of your stress and responsibility, but by no means all of it. You continue to share the burden of this office until about 8:00 pm, when it can finally be shut down for the night. Also keep in mind that the office can decide that it needs to keep running past that 8:00 time slot, and/or it can decide it needs to be running at a later time - say 12:30 am or 4:00 am - it's in charge, not you. When 8:00 am rolls around again, your partner runs off and you are on your own again.
You would think that such a high-stress job would offer weekends and holidays off, but sadly you thought wrong. Weekends and holidays you do get to have your partner there with you, but you cannot leave that office. Maybe you can pack up all of the important things you need to run your office and take it with you, so that you can run your office while taking care of other things, but the office is always your first priority. Once and a while you can hire someone to care for you office for you for short amounts of time, but they will never do as good a job as you, and your office will protest.
Now before we go further with this story you must also keep in mind that you chose this job freely and willingly, and YOU DO NOT GET PAID! Not at all - no monetary compensation of any kind.
Back to this partner of yours. Yes, they are a huge help to you. You live for the times when this person shows up and helps you run the office, because while it was agreed to by the both of you that you would be solely responsible for the office to that they could find a way to earn money for your business, you are both equally attached to this office. Partners 50/50.
Let us remember here, because I cannot stress this point enough: This office belongs to the both of you equally!
So tell me please, is it fair for this partner of yours to assume that just because you care for this office single-handedly the majority of the time, that it is okay that they make plans in their free time and not give you equal opportunity to do so as well? No it is not!! But you see, they don't understand that running that damn office is all you do. That though you care about the office immensely, and running an office just like this is your life's dream, you can't be expected to do it 24/7 all the freakin' time with no break. They wonder why your patience is running thin and your temper is short, but they don't understand why. Is your partner blind? No, not at all. Is your partner stupid? No, far from it. Then why in the world do they not see that anyone who does any one thing without a break is going to go mad?
This is not a hypothetical question - if anyone can answer this one I'm open to ideas. It is beyond me. I mean, after all, this partner of yours likes to get away from their day job and have fun. You would think they would understand.