You seriously think most Thai girls can Hope to secure a young, attractive, wealthy Thai man? Have you ever even been to Thailand? Young, attractive, wealthy Thai men literally have their pick of the women and are likely to be unfaithful.
Jesus
And the culture and language thing is not as much of a challenge as you think. This might be a shock to you, but foreign people are allowed to learn Thai culture and the language and many Thai people even learn English now.