Same Sex Common Law Marriages will not happen in Texas, because Texas Communities do not recognize Same Sex Marriage.
A necessary element for a Texas Common Law Marriage is the Holding Out. A Same Sex Couple could not hold themselves out to the Community as Married. Texas Communities do not recognize Same Sex Marriage, and neither does Texas Law.
An Equal Protection challenge could not be sustained because the Equal Protection of the Laws Clause of the Fourteenth Amendment does not create rights that do not exist. There is no Constitutional Right to a Same Sex Marriage.
In Texas Communities are built with Families consisting of Mothers, Fathers and Children. A Same Sex Couple cannot have children.
The Community has a First Amendment right to Freedom of Association and to establish the Values of the Community. Same Sex Couples have no right to destroy the Values and First Amendment Associational Rights of the Texas Community. The Equal Protection Clause was never ment to be used as a Weapon against the Community.