Imagine there are two land masses next to each other. One much larger than the other. We’ll call them Big and Small.
Most of the people living in Small want Small to remain independent from Big. There is, however, a significant minority of Smallites who value links with Big so highly that they’d like Small to be governed from Big.
So the Small government hold a referendum and discover that about 1 in 6 Smallites wants to be governed by Big. They also discover that this minority is concentrated in the areas of Small that are geographically closest to Big.
What happens is that Small becomes partitioned. The part of Small containing most of the Big-friendly Smallites becomes a part of Big and the rest of Small continues as an independent country.
Is this a good thing?
How about if we use other names instead of Big and Small. Assume Big is the UK and Small is Ireland. Or (more interestingly) assume Big is Europe and Small is the UK.