In my life there are a number of people who don't seem to "get" that what they think I can afford and what I can afford are not the same. I do not make a lot of money ($63K/year), but it's a lot compared to many of my friends and family members.
Somewhat similar situation here. My Aunt (who we love, she's a very nice person) made the comment of "but you can afford that" when I said we weren't going to also go to Sydney with my mom, which means she'd miss out on that, and she SO wanted to do that. I try not to give specifics too much, but I pointed out how much it cost the FOUR of us to fly to New Zealand to meet my mom (flights were cheaper for her to fly to New Zealand and then to Australia), because she SO wanted to see New Zealand. That cost a lot for us, for all of three days! I just wasn't going to do it again; Sydney would still be there and my mom could make sure she makes it there next time.
My mother assumes that because "you make all that money," I am able to pay $100+ for the buffet for her and my dependents for her birthday celebration. I had been intending to hold a cheaper celebration at my house where I did the cooking. When she said she really wanted to go out for buffet, my brother changed the plans and suddenly I was stuck with the bill. My sister, who also makes about what I do, was similarly frustrated. No matter how many times I tell my mother that it might seem like I make a lot of money, I have many expenses and want to save so that I can pay off my house and retire in 5.5 years, she doesn't get it.
Wife's mom is like that. Bit more subtle though, she'll just take forever to get out her money to pay at a restaurant (so you'll give up and just pay) or not offer to pay for whatever groceries you picked up for her at Walmart. My wife's sister falls for this too often I believe (which can cause resentment that my wife isn't chipping in for "her half"). My wife however will simply wait the 5+ minutes it takes for her to pay a restaurant bill, and will remind her of how much the groceries cost that she needs to be reimbursed for. Might not have gone over that well the first time or two...but guess who doesn't get asked to bring groceries every time they visit?
I don't know what he said to his gym teacher (who is a friend of my boyfriend's), but he came home with a pair of used but good condition shoes that the Phys Ed department has for kids who can't afford decent athletic shoes. Gah! Gym teacher is a colleague of mine and has a heart of gold. But Jeez. My son could have waited until the end of February.
I can somewhat relate yet again! Our son's school has these fundraiser stores for certain holidays. I.e. for Mother's Day and Father's Day, they can take a $1 or $2 coin and buy some cheap crap to give you as a present. For Mother's Day I explained to his teacher that he would not be participating and why...she said they'd probably send him home with something anyways (which they did). For Father's Day I specifically asked that they not send him with something; we had discussed it with him, told him he could buy something with his allowance if he wanted, but we'd prefer something he had made instead (such as a card); well he'd taken some things he'd made at the hardware store to school (to show), they helped him wrap it up as a present for Father's Day. That was nice of them. I know they meant well when they sent him home with something for Mother's Day...it's not that we couldn't afford it, but that it wasn't in line with our (or his) values.
I have explained and explained to the people in my life that I can't afford to do what they want many times. Why are they not getting it? Maybe by giving in and paying for that buffet I sent the wrong message. It meant I had to seriously cut back in other areas to afford it and I really did resent that, but I did give in that time. I won't next time. I don't give in the other times, but still people aren't getting it.
You have to stick to your guns. They've gotten you to pay in the past, so they've been "trained" to act that way. It takes a while to un-train that behaviour.
But do note, this could cause a big issue within your family; some may refuse to speak to you again. You have to decide if it's worth the risk. There are multiple people in our family that no longer speak to us (one probably permanently, the other has been a few months now so I dunno how that'll play out). All related to money.
How does everyone manage to deal with others who don't get that while it might seem like we can afford it, we either don't want to or can't?
Well, we just explain that we have different priorities, that we choose to spend our money on certain things (including saving for retirement). Of course, many people just won't get it, so just roll up a newspaper, smack them on the nose, and say "No! Bad spendthrift, bad!" Wait, no, got my "Dog Discipline Training" book confused with my "Financial Discipline Training" book again.