Could Texas and the United States simply negotiate a separation agreement?

Yes. A negotiated separation is not only legal, it is the most likely path, and it is the one the modern world uses. Even the Supreme Court case opponents cite against Texas concedes that the union can be dissolved through the consent of the states.

The case they quote against us admits the exit exists

In Texas v. White, the 1869 opinion that is the entire legal foundation for the "Texas can't leave" claim, Chief Justice Chase wrote that once a state was in the union "there was no place for reconsideration or revocation, except through revolution or through consent of the States." Read that clause again. Except through consent of the states. The very opinion held up as the iron door has a key sitting in the lock. Chase conceded that a lawful, peaceful exit by consent exists. Opponents quote the first half of his sentence and skip the part that gives the game away.

Consent is how grown nations part ways

A negotiated separation is a constitutional transition, not a war and not a collapse. It is the path Scotland was offered in 2014, the path Quebec voted on in 1995, and the path the Czech Republic and Slovakia actually walked in 1993 when they divided peacefully into two countries in about six months. These are orderly, lawful processes governed by agreement and recognized by the world. The Confederacy is not the template. Brexit is, and an amicable divorce between two governments that decide to go their own way is older than that.

A clear vote creates an obligation to come to the table

The legal architecture for this already exists in the democratic world, and the leading example is Canada. When Canada's Supreme Court considered Quebec in 1998, it held that a clear majority on a clear question would create a binding duty on the rest of the country to negotiate the terms of separation in good faith. The court was direct: the other partners "would have no basis to deny the right of the government of Quebec to pursue secession" after such a vote. Canada then wrote that principle into law in the Clarity Act of 2000. A clear expression of the people's will does not get to be ignored. It opens negotiations.

What the negotiation actually covers

A separation agreement is detailed but entirely ordinary in its subject matter. The Quebec framework lists the kinds of questions on the table: the division of assets and liabilities, the treatment of borders, the rights and interests of affected populations, and the protection of minority rights. For Texas the agenda would include trade, the status of federal facilities, currency continuity, citizenship and benefits, and the rest. None of it is mysterious. Nations have negotiated exactly these terms many times.

The choice belongs to Washington, not to Texas

Here is the structure of it. Texas asks the question. The people of Texas answer it. After a clear majority votes to restore independence, Washington faces a decision, not Texas. It can recognize the result and negotiate a clean, mutually beneficial separation, the path that keeps trade flowing and the border calm. Or it can refuse to honor a peaceful, democratic vote, which isolates it internationally and serves no one. The practical, stabilizing choice, the one nations almost always make, is to negotiate.

The bottom line

Texas and the United States can absolutely negotiate a separation agreement, and that is the realistic route to independence. The case cited against us concedes that consent is a lawful exit, the democratic world has a working model for it, and a clear vote of the people of Texas is what starts the conversation. Consent is not a permission slip from Washington. It is a vote of the people of Texas that Washington then has every reason to honor.