The main reason so many marriages fail is a lack of commitment to succeed, to compromise when necessary. Usually by both sides, with the caveat that one or the other has often developed on adulterous sex interest (even if not yet acted upon). Part of the purpose of dating and having a pre-marital relationship (excluding intercourse), is to test the boundaries of behavior compromise to insure that there are no break up issues. (Sleep with window open/ closed)

Being happily married requires commitment. And working on it. And maybe some practice of suffering together (the modern unwritten ideal of avoiding all psychic suffering leads to shallowness), comforting each other, and accepting the differences.

With society focussed on the materialistic and consumeristic, such lack of commitment is implicitly encouraged.

The totem pole certainly does matter; but it's also true that adoption decisions, like pregancy, are either yes or no. I don't doubt that the best gay couple would be better parents than the worst hetero parents accepted.

I'm also sure that the most skillful drunk driver is a better driver than the worst non-drunk driver.

But even the best gays have the obvious problem that they couldn't, biologically, have been the birth parents.

The pro-gay adoption supporters, not sure if that's all pro-gay marriage folks (haven't read otherwise), certainly seem to want to change society to be one where biology doesn't matter so much. As of today, biology does matter, a lot; and thus, today, there will certainly be strong external pressures on and around any child that is raised by gays.

Since legal custody of an adopted child rests with a government decision, and allowing a couple to adopt is a priviledge, it would be wrong/ bad for the child to allow gays to adopt the child while so many in society oppose it.

This is unlike the right of any fertile woman to conceive, no matter how poor a parent the woman might be.