Motherhood and apple pie

With so many marriages ending in disaster or, if not disaster, at least early closure, is it time we had a rethink about the role of marriage, not from a societal point of view but from an individual point of view.
The conservative catholic teaching which most of us over a certain age absorbed as sacrosanct is challenged all the time by the growth in single motherhood. Putting aside the economic aspect of funding the raising of a child, is there any opposition, other than the religious one, to the single parent, child rearing formula which is becoming common. This includes both gender since it has to be assumed that a man can be as much up to the task as a woman, although observation doesn't quite bare this out since one sees what seems instinctive in a woman, the full time attendance to the child's needs, in a man even with the best will in the world his attention can drift.
But before I get sidetracked, it's the psychological imperative of marriage that I am questioning.
In the age when we had breadwinners and home makers the guidelines were clear and the roles set. Now with both men and women working and both trying to contribute to the home making have we not reached a stage when either gender is ambidextrous and apart from the act of copulation (even that can be sidestepped) there is less and less need for the other in the mechanism of child rearing. This is not to say that in a balanced family the absorption by the child of gender characteristics isn't useful, the question is, is it necessary ?
In a Gay household one or other gender is missing and whilst there is some stereotyping role play in the home, the dominant, sub-dominant, it seems that the influence or lack of influence has little or no effect.
Gay children are the offspring of heterosexuality and heterosexual children are the outcome of Lesbian or homosexual homes with of course the caveat that there had to be a member of the opposite sex involved in the process at the beginning.
Again I am in danger of being sidetracked.
What I am getting at is, do people put too much store on finding the right man or women and getting married. Is it a societal thing first and foremost.
I see the other day, in Japan, a woman of 72 married to a man of 76 has just given birth the a baby. The conclusion has to be that physically it's possible but emotionally, for the child, is it fair.
Is it fair for a child to be brought up in the home of two Gay people. Is it fair for a child to be brought up in a home where there is only one gender to mimic and role play as the child forms its opinions from its environment.
We have to say yes since the opposite case, of growing up in a dysfunctional family with all the wrong gender signposts in place the tendency has to be for a poor outcome.
If the so called magic of the church blessed happy family is rare then we are left with the church of, make do and best intentions.
People rise up and prove the opposite to convention, they prove that resilience and common sense are the best ingredient for life in general and we make of our lives the best when we are able to rise above the confines of societal norms and stamp our own personality and character on what ever we decide to do.