I hope i do not offend you with what i am going to type. I am just relaying what i heard from my friends as well as girls that works in the nightlife. Through the various gossip sessions.
Many many years ago Caucasian men are highly sought after customers/life partner in thailand because of their spending power due to the strong currency. Over the years, the consensus started to change. Dollar, pounds, euros became weaker. The caucasians are not spending as much. There is a huge invasion of backpackers that are spoiling your reputation. A good example would be bali. Hear what the locals has to say about the caucasians and you will know that its whats happening in thailand as well but just not that serious.
As the years goes by, other countries started to catch up. Countries such as china and korea are bagging more girls now. Better looking girls as well. Singapore, Malaysia and japan has always been in the middle ranking i think. We are always a safe option but we are never as big of a spender as the PRCs. Not as handsome as the koreans.
I will generalise and split thai girls into 2 major category. The light skinned and the dark skinned girls. The lighter skinned girls with sharper features now prefers to go with Asian men because they feel that asian men tip better. Additionally, they are not as PAINFUL.
The darker ones because they are not as well received by the asian men will still be willing to accept the caucasians. Which is what you usually see on the streets. A white men (regardless old or young) with a dark skinned thai girl.
My guess is that the girl you chose belong to the first category?