Gay marriage - why not dump marriage?

I have to first declare that I am neither gay nor married and thus I have been watching the recent furore that has engulfed UK political parties with a degree of abstraction, not to say indifference, but in all the arguments it seems to me that one solution has been missed which seems blindingly obvious. Why not abandon marriage as a legal construct altogether?

I am not here sounding the death-knell for marriage which is a long-standing and vital institution. It is not the place of the state in my view to dictate who should marry whom.  The state is only concerned with the legal ramifications of such relationships.  There would be nothing to stop you getting married, making a personal and social commitment in or outside a faith context if marriage were taken out of the legal context.  At present you have to register a marriage for it to have legal effect.

If I am not writing this as a gay or married person, then I am writing it as a life-long feminist.  The status of women has changed dramatically in the past thirty years and I like to think I have had something to do with it.  Most of the anomalies in our marriage laws derive from the fact that they were conceived at a time when women were financially dependent on their marriage partners.  This is no longer the case.  To remove the anomalies it seems to me the best solution would be to simply take marriage out of the legal equation. 

I am now for example a single pensioner.  Were I to decide to marry to spend my twilight years in someone else's company my pension, which I now hold as an individual, would become swallowed up in a 'married persons' pension' and be payable to my husband.  This seems to me deeply unfair and frankly I would have to think long and hard about sacrificing my financial independence.  This is an example where the state decides, for no very good reason, to treat a married woman as if she were not an adult person capable of managing her own affairs.

It seems to me that if the law were to treat all individuals, whatever their relationship, as legal equals many of the anomalies would simply disappear.  Rights between couples would be established purely by legal documentation - joint mortgages, wills etc. and there would be no situation where for instance a wife might automatically inherit even though she is no longer co-habiting with her husband.  In this way the law would be applied whatever the gender of the couple and the whole problem of changing the nature of marriage as a social or religious institution would not apply.

The UK Conservative party has got itself into a terrible tangle by using the term 'gay marriage' which has sent its more conservative members into a tailspin.  If instead the party had talked about updating UK law to simply remove the anomalies introduced by treating marriage as a legal condition most people would I think be in favour.  It will be complicated because there are so many layers of legal precedent but in the end you would have a fairer legal system.