The public dimesnsion of marriage has been marginalised and diminished by the culture for many decades now. This undermining and betrayal of marriage is responsible, in large part, for the current UK proposal for same-sex marriage to be legalised.
Marriage has a public dimension. It is an essential aspect of marriage. This dimension is expressed formally in whatever marriage ceremony takes place by the presence of witnesses. A contract entered into privately by two parties has never been considered as marriage; society, represented by the witnesses, has to be present in order that this coming together by two people might be understood as marriage.
The public dimension is a part of what marriage is because there is a relationship between marriage and society. Society depends upon marriage (for the procreation of children and their upbringing), and marriage depends upon society in order to assist it in its mission. It is a mutual relationship, but not one in which marriage and society are as equals, for society (but not marriage) is obliged to observe the principle of subsidiarity, because marriage (and the family) takes priority over society.
The diminishing of the public dimension has been taking place over recent decades through a number of ways. We have the culture-led and State-led project of contraception and abortion. We have the culture-led and State-led project of divorce and the trivialisation of sexuality and relationships. We have the increasing number of people who have chosen not to get married but to simply live together. All of this has conspired to create an ethos of life without social responsibility, and in terms of marriage, to make the social dimension of marriage seem like an unbearable imposition.
So, in such a subjective age we hear such opinions as this: "What you are talking about (same-sex marriage) is individual people and their personal relationships, their love for each other and their wanting to be in a partnership or getting married. I think we should support that." (Harriet Harman, Labour front-bencher)
The culture has tried to remove the social dimension of marriage so that now we are in that position as a society where people want to do exactly what they want, without any sense of their responsibilty towards society, whether this is heterosexual or homosexual co-habiting. Same-sex marriage can never be in a right relationship with society because of the impossibility here of procreation, and of the authentic nature of the upbringing of children.
A important factor for young people today who are in relationships is to take your relationships out of the purely private sphere and introduce them properly into the context of family and friends, but especially family. Because if you marry, your life will be lived among and supported by your families, and by society also, not to mention the Church.