The thing is, it's a little bit like giving in to a tantruming toddler because you love them.
They never learn that it's bad behaviour, because that behaviour is always effective at getting their own way.
So give in on the wedding, and then they'll always expect you to give in, because you've always accepted their bad behaviour.
Look further down the line to buying houses, organising a christening (or not) for your DC, decisions about where to spend Christmas Day, about parenting your child, about their schooling etc etc etc
My PILs are lovely but expect to be in charge. We gave in for a quiet life when we were first married which worked fine until we had children and we couldn't give in.
The relationship has been far more difficult ever since. My biggest regret is not drawing a line in the sand as soon as we got married.
It's not about falling out or confrontation, it's about being an adult and making your own choices.
If they love you as they and you say they do, will they really cut you off over this?
Because if so, that's a pretty pallid immitation of love.