Does Common Law Marriage really exist in Houston, Texas?

Yes, really. The three elements are agreement that you are married, cohabitation and holding yourselves out in the community as married. The fact that there are no documents or writings proving any of these elements does not prevent a court from finding a common law marriage if there are other kinds of evidence. Even oral testimony alone is enough if the judge (or jury) believes it.

Common law marriage is a valid marriage in Texas.