It just seems wrong to me, kind of like not allowing divorces. If states don’t see eye to eye on most issues anymore, why should they be forced to stay together? Forcing 2 or more parties with wildly different outlooks on things to stay together just creates division and conflict. Everyone should be allowed to go their own way, for their good and others’. Saying this as someone from Massachusetts - I’d really support my state seceding and forming some sort of federation with other like-minded Northeastern states.
Every case is different and the UK as a political union without a written constitution can technically allow one of their four home nations to become independent (again).
The US has had bad experiences with seceding states. Big kerfuffle that people didn’t want to repeat.
When it comes to international recognition of seceding territories, it’s frankly a mess. And also, frankly, everything is possible. Kosovo is an example where the majority of the international community decided to recognize it as a sovereign country. It was a solution to a war situation that didn’t make all parties happy. Serbia and Russia, for instance, still don’t recognize it. So while Mass may not technically be allowed to leave, if it did anyway, it would depend on the reaction from the rest of the union first and foremost, and then on the international community. If they back you and maybe even send peace keepers, there is a chance still. But there is a whole laundry list of things that have to go right for this to happen.
I’d suggest you devote all your energy to fixing the United States first. Resist 47 and his GOP cult followers. Not all is lost just yet.