I anticipate abuse from anyone and everyone from all corners of the political spectrum, and I hope there's something in it for everyone (to get all offended about).
I loathe the term "partner". For me, and all civilised people, the progression is Girlfriend-Fiancee-Wife. A "Partner" is someone with whom one does business. Anyway semantics aside, one's girlfriend, if she lives in the same place is now deemed in law to be a "partner", and as such deemed does not qualify for any out of work benefits should she become unemployed beyond Job Seekers' Allowance (assuming a history of recent NI contributions). The working "partner" is responsible for the non-working one, saving the country thousands in benefits, yet as far as I can see, the working partner (usually the man) sees no benefit from taking on this responsibility at some cost to himself.
No-one seems to bat an eyelid about the fact the decision is made on whether two people who live together are "in a relationship". The question is therefore one of sleeping arrangements and sex. Were you shagging your lodger, any benefits (s)he may claim would become fraudulent. This gives the state a prurient interest in people's bedrooms, hence RIPA and bin-snooping by council prod-noses. This represents a gross intrusion into people's privacy.
This is also grossly unfair on the working partner, who may find himself (for it is usually a 'He') with financial burdens he was not expecting and did not want.
Marriage should be the contract under which two people should be bound together by law, where they take fiscal responsibility for each other and any fruit of the union. Taking this logic one stage futher, surely women would take more care with their fertility if they did not have access to a man's wallet should they "accidentally" fall pregnant. After all, I thought the whole pill, 60's feminist revolution and all that was about the "woman's right to choose" put a woman in control, taking that control from the patriarchal phallocracic oppression rape-matrix, or whatever it's called in sociology classes these days. It should indeed be the woman's right to choose, but not at the man's expense. Sex is not an open offer of fatherhood. That, I thought was the other side of the whole 60's feminist revolution? Don't like abortion? Pay for the kid yourself, or keep your legs shut until you find a man willing to commit. It is after all, a woman's right to choose.
Marriage would be the contract under which a man declares that he takes responsibility for his wife's children (assuming they're actually his...). Marriage would be the contract that he agrees to pay his wife's bills when she's unemployed. In return, he (for it is usually a he) should get to enjoy his wife's tax allowances by allowing her to take some of his salary. Obviously, working women keeping a beta male at home should enjoy the same advantages. "House-husbands" will remain risible, emasculated creatures, however much the Guardian wishes they weren't, but the tax-system should not discriminate between the sexes, and should allow people to make life-style choices as they see fit.
At the moment, the tax and benefits system is a standing invitation for both sexes to behave appallingly to each other, but in financial terms, it is horribly weighted against men, who bear most of the risk, and enjoy few benefits of any form of relationship with the opposite sex beyond soulless condom-covered one-night stands.
And though social conservatives were wrong about gay-rights, for example, they're right about marriage: Because any form of co-habitation is now essentially the same as marriage in the eyes of the law, marriage itself becomes devalued. Thanks to liberal legislation without an eye on the unintended consequences, the flexibility of the genuine lifestyle choice of uncommitted co-habitation has become impossible, thanks to legislation generally opposed by social conservatives: the social Liberals have generally sought measures by which they perversely limit freedom. By all means campaign to remove social stigma, but by seeking to liberalise (by removing any penalties against unmarried co-habitation) any co-habitation, in essence becomes a marriage, whether the parties want this or not. Allow people to choose to be committed to each other. The state should not be forcing the issue.
The grey areas of co-habitation and "long-term partnerhood" should be relegated to mere social descriptors. Marriage should be the sole and only declaration by which any two people are bound together and have responsibilities to each other in law. Thus in the timeless words of the book of common prayer that marriage, and the responsibilities it entails should not be...
...enterprised, nor taken in hand, unadvisedly, lightly, or wantonly, to satisfy men's carnal lusts and appetites, like brute beasts that have no understanding; but reverently, discreetly, advisedly, soberly...... are as true today as they were when they were written. Marriage is a life-style choice like any other, but it is one which entails enormous responsibilities and risks, especially that of child-rearing, and promising to support another person through thick and thin; and those risks should not be forced on anyone. And because everyone benefits from stable families, it's only fair that those risks should be recognised in the tax-system.
So. The Coalitions slain the post-war shibboleth of universal benefits. In return for middle class mums losing their child benefit (spent mostly on white wine), Dad should get a lower tax-bill. Of course, though they might not say it, the reason the lefties are so against the means-test for child benefit, even though it means they have to argue in favour of state hand-outs to millionaires is the same as they argued against top-up payments for NHS treatment. The principal of universality is one by which the people who pay for the welfare state - those on middle and higher incomes - feel they get a little back. Now this principle is broken, we will see a steady decline in support from the middle and upper earners (who together form a majority) for the welfare state in which they have no stake. They will instead start arguing and voting for lower taxes. Middle and upper income earners are more likely to vote. This is something the more intelligent lefties have noticed.
The left would rather tax someone, then give some of that back as a benefit, simply to keep the tax rolling in to pay for Labour's client state. This is inefficient, unfair, and frankly idiotic.
The mooted recognition of Marriage in the tax-system is going to be presented as a sop to the Tory right. But will it be a means by which the manifest unfairnesses of the means by which the relationships between the sexes are governed will be addressed, by allowing the furious objections of the left to be dismissed as what they are: divisive political dogma.