What is commonly known as a premarital or prenuptial agreement (prenuptual) is not a new idea either legally or culturally. Women have wanted assurance that in the event of a divorce or death of a spouse that they wouldn't end up homeless.

"People have been making prenuptial agreements for thousands of years. Scholars tell us that the practice dates back to the ancient Egyptians, and that prenups have existed for many centuries in Anglo-American tradition. In previous times, the parents of the bride and groom negotiated the agreement on the new couple's behalf."

Source: Prenuptial Agreements: How to Write a Fair and Lasting Contract, page 1/2.
by Katherine E. Stoner and Shae Irving

Thailand adopted Civil Law. And under Civil Law, a marriage is a contract. Therefore, parties can decide HOW they would like to enter into this marriage...

Examples of Prenuptial Agreements in History

"The Ketubah, the Hebrew marriage contract dating back 2000 years ago, is one of the first legal documents giving financial and legal rights to women.

Dowries, often considered to be early prenuptial agreements, were mentioned in seventh century writings as a necessity.

Edward IV reportedly had a pre-nuptial agreement with Eleanor Butler sometime between 1461 and 1464.

Elizabeth Oglethorpe, in 1744, before getting married, required General James Edward Oglethorpe to sign a prenuptial agreement protecting her property rights."

Source: about.com

Today, a prenuptial agreement is a common agreement. In some countries like The Netherlands, it's very common. There is nothing wrong wanting to protect your assets and it doesn't mean that you don't love your spouse. But today, about half of marriages are ending in divorce. Therefore, you should think about your future and in reality, we never know what will happen one, two or ten years from now.