kate oh do shut up. We are in 2019 now.
So... do you never do anything ever that impinges on your own immediate personal happiness for the sake of your partner because it's 2019? 
'Can I switch over to the football?"
'No, it's 2019 and I don't enjoy football!'
'My mum's popping over this afternoon for a cuppa, that ok?'
'No, it's 2019, and although she's always nice to me and brings us flowers, I don't like the way she talks about knitting'
My parents were here last weekend. His parents will come over this weekend. Neither activity is wildly enjoyed by the other half, but I suppose since it's 2019 we'll have to divorce, because a bit of non-optimal enjoyment isn't an option.
Mil knows about my bunions and how walking for hours can get painful
Right... so instead of politely saying that, and wishing them well, you sneerily said it would be boring (there really isn't a way not to sneer when you're declining an invitation on the grounds that it would bore you...). I'm beginning to see why MIL has a problem, and it's nothing to do with class, rather the graceless way in which you communicate your feelings.