I've been in a similar position- moved to DH's town and lived there for 13 years, had very established life there. However, I said to him right at the start of the relationship that I didn't want to live there forever and made sure he was ok with that. We have now moved to where I was from (more rural, by the sea etc). The trigger point was my mum's ill health - we thought we might lose her, and I couldn't bear being so far away.
There are pros and cons to the move. We are quite isolated where we are which was good during Covid (😂) but when you want to travel anywhere or find opportunities for dc it can be a pain. We miss our friends and family from our old life and it has been tricky keeping up with everyone, however good your intentions are. Likewise it has been tricky settling in here thanks to the pandemic - making friends and social opportunities few and far between. DH is unmoved by the coast/countryside - he wouldn't be here if it wasn't for me, he doesn't care about being near the sea. He also had to leave his job - which he liked to start with, but not many employment opportunities here so he is now a bit frustrated.
It took Dd a long time to settle here, probably a year and I did feel guilty about dragging her away from her friends, school, cousins etc. it's better now.
It also gets soooooo busy here in the summer that you can't go out and enjoy the countryside because it's crawling with tourists, you can't park, everything is booked up 😂. So bear in mind it might not be as fantastic as you imagine in your head!
Now you have broached the subject with DH you need to allow him time to adjust to the idea. Try to do some research into the realities of the move - houses, schools, jobs etc so you can continue more discussion at a later date. He may warm to the idea. If it is something that is so important to you he should give it full consideration before dismissing, even if he doesn't want to move.