I read some interesting stats:
"In the UK there were over 400,000+ marriages in the 1970s (80 marriages per 1,000)- there are now around 230,000 (20:1,000), even though the population is increasing! Marriage is basically a D.E.A.D. institution."
For how bad the situation really is: https://www.ons.gov.uk/peoplepopulationandcommunit...
Currently gay marriage is the latest debate about Marriage. Many countries are embracing it. However conservative forces (like the Church, Christians, etc) are opposing gay marriage. Some argue that a change in the definition (a union between a man and a woman) could open the back door to polygamy, etc. Others that it violates the Bible and some argue that its turning our back on core societal (or conservative) values.
But I really think this is missing the point. Those who are trying to 'protect' marriage have already failed. It is a dead institution. The marriage rate is falling and falling from 80 per 1,000 to 20 per 1,000. The only way to stop the continued falling marriage rate is to re-introduce restrictions on divorce (no no-fault divorces), but of course this will not happen.
The conservatives are trying to fight gay marriage to protect the institute of marriage, but that war has already been lost.