There’s a good piece here on the large age gap often found between Western men and their Thai brides. This is really an excellent article. It’s on the website for the English-language Chiang Mai News up in the North.
I love the old guy they found to pose for the article. 
Full disclosure: I know a few of these May-December relationships, but as for myself, I’m only two years older than my Thai bride. (Two years, one month, one week and four days to be exact.)