My two cents.
Marriage is different to a wedding. A marriage can be made legal in ten minutes with no fuss.
A wedding on the other hand can be the catalyst for a lot of angst, expense and family bust ups. Not to mention the expense of attending a meal, which is all it is really.
So a wedding is in the Lake District and you live in Dorset, for example. And you have three or four or more or less DCs that need minding. And you have a humungous mortgage and bills to be paid and want to prioritise and budget accordingly.
So you get this summons, sorry invite and think WTF will we do here.
Well folks, do what I do if you want, but it works for me. Weddings are for the Bride only, Groom just goes along. Sorry reality here.
So unless it is immediate family I send a gorgeous card with a decent cheque (cancel the cheque immediately lol, another thread), and send a lovely well thought out and genuine message as to why we cannot make it.
Sorry, there is no way I am going to eat a chicken/duck/lamb dinner for the cost of a dress, shoes, overnight stay, cost of getting there and back and having to sit with people I don't know for hours. Sorrrryyyyyy.
Not going to happen ever again for us. Been there.
Still, as long as we give a generous monetary gift (which is so much less than the cost of attending) it's all good. Who will miss us if it is not immediate family, which I do like to attend as we are all ok with each other and have a ball.
It is the non immediate family weddings that are "sorry, cannot attend, hope you will be very happy" kind of replies to the summons, sorry invite.
And I reckon both sides are happy with that!
Do what makes you happy as an invitee. You do not need to feed the Bridezillas.
But each to their own.