We have an interest in the fate of Britain, IMO.
They have the only military force of significance east of Maine. The EU is, so far, a farcical talk shop with no ability to carry out their silly, pompous threats to obstruct our freedom of action. There is no prospect (yet) that Germany, France, and Italy could or would create a military force to oppose us.
Britain is a different matter. If Britain falls to the EU, we will at best lose their fighting forces as allies-at worst, they will become enemies.