"Male homosexuals (MSM) are defined by who they like to have sex with, NOT by who they love."

True, as it is true that heterosexual are defined by their sexual preference.
The two terms define sexual preference.

"Heterosexual marriage is an excellent template for society, but the prevalence of "open relationships" amongst the male homosexual community is extremely risky and unhealthy in today's sexual climate."

Do you really deny that multiple concurrent partners is risky and unhealthy?
NAT states it is the cause of high infection rates.

"Many male homosexual relationships, unions and "marriages" are "open" by common consent."
I am sure many are, so that is a statement of fact.

"As such, they are radically different from conventional heterosexual marriages which are for the large part monogamous.

Open marriages ARE different from conventional monogamous ones.