I agree with both Karen and Marcus.
I'm heterosexual and happily married. I cannot see
any way at all that
my marriage is threatened by same-sex marriage - and I know people who are married to their same-sex partner (here in Canada, where same-sex marriage is legal and now accepted as quite normal) and their relationships are stable, unremarkable and happier than many heterosexual marriages I know. I work with one half of a lesbian couple who have just had a baby, and they're incredibly happy and the baby's being showered with every bit as much love as the children of heterosexual relationships I see around me.
As Karen says, anyway, aren't children supposed to be better off with two parents, not one? I thought that was the argument of the social conservatives over the past 20 years or so.
Wendy