The Mistress’ Mister

I have always wondered what the male equivalent of the mistress is…Mister? I came across this article, though a few years old, is an interesting thought and history of the male mistress role, the mister (tongue in cheek, I think).
See the article here: http://www.huffingtonpost.com/elizabeth-abbott/if-he-has-a-mistress-why-_b_966332.html