@JLeslie “Edit: one thing to know is there is an agreement between states to accept marriages in other states as valid. So, when you marry in Florida, all other 50 states, DC, and US territories accept Florida’s legal marriage the same as their own.”
Well it’s not so much an agreement between the states as it is Constitutional law. Specifically the Full Faith and Credit Clause (Article IV, section I). Whether it’s a marriage, a divorce, a custody agreement, a contractual agreement, et all legal rulings, proceedings, etc in a state must be honored by every other state in the union.
Although, this particular clause was not invoked by the SCOTUS in Obergefell v Hodges (the ruling which legalized same-sex marriage throughout the United States)*. In Obergefell v Hodges the SCOTUS cited the Equal Protection Clause of the 14th Amendment. The same clause cited by the SCOTUS in Loving v Virginia (1967), which struck down state laws banning interracial marriage.
(*Before the Supreme Court’s ruling in Obergefell v Hodges I had once figured that, with the hodge-podge of various state laws regarding gay marriage springing up, the Full Faith and Credit Clause would eventually be invoked to force one state to recognize the legal marriage of a same-sex couple married in another state. Thus making same-sex marriage de facto legal in that state and all others. Happily I turned out to be wrong there.)