While recent legal and legislative progress that has expanded the rights of same-sex couples to marry, the truth is that many couples have been functionally married for many years even without legal recognition. So, while many have been officially "tying the knot" only in the past few years, they have already shared property, had children, supported each other's careers and all of the other things associated with a legal marriage.
The discrepancy between the actual duration of the relationship and the legal ability to marry is often not a big problem during the relationship, but when those marriages end, it can be a very complex divorce process.
The issue of when the marital relationship began compared with when the legal marriage started is a relatively new problem for courts. Divorce law measures only the time that a couple has had a legally recognized marriage, which impacts which property is divided and how much spousal support must be paid. Ignoring the first five, ten, or even 20 years of a relationship before a marriage was legally recognized can produce some strange results in a divorce and can often force the parties to work out the pre-existing property issues on their own without court supervision or the benefit of binding state family laws.
Another problem that same-sex couples face, particularly here in Nevada, is the pathwork of laws in various states around the country. If a same-sex couple has foregon the option of being a registered domestic partnership here in Nevada in favor of a legal marriage in another state, there may also be issues of which laws apply and where the divorce should take place. Many states will not allow a divorce case in their courts even if the couple was legally married there unless one or both spouses has lived in the state for a certain amount of time (often six months to a year). For some, this may mean that a costly move across the country is a necessary part of the divorce process.
Source: Today.com, "For gay couples, divorce comes with extra costs," Eun Kyung Km, Aug 6, 2013