My objection is, that in the main male homosexuals do not appear to have an interest in long term relationships or monogamy, examplified by the low take up rates of civil union, or homosexual "marriage" where available and the short duration of these unions/"marriages" in general terms.

It seems to be accepted even here, that studies and health figures show that male to male sex carries huge rates of promiscuity endemic to that type of sexual behaviour.
As I have remarked before the comparison of male homosexuality and monogamy, looks very much like the one between chalk and cheese.

Gay "marriage" legislation......smokescreen.