While the trouble the gay community has with monogamy is a commonplace- freely admitted by gays, as a rule, when they aren't trying to promote the concept of gay "marriage-" the Dutch study which is often used to document that difficulty in fact does not offer support for the conclusion that "married" gay men are nearly as promiscuous as those who cite it claim, nor that gay "marriages" tend to be as short-lived as is claimed. The study based on a study of legally-partnered AIDS patients, and not of legally partnered gay men as a group. So what it says about "married" gay AIDS patients cannot be fairly extraoplated to prove anything in particular about "married" gay Dutch men in general.
I've just deleted a post from several years ago based on that study. The fact that monogamy is not necessarily an expectation for "married" gays stands- but it seems that the statistics I quoted are a distortion of the data, so I want to clearly disavow them.