This isn't very liberal is it?

We've just spent a couple of centuries enshrining in the law the idea that consenting adults can do, in matters sexual, pretty much whatever consenting adults wish to do. This is one of the great liberal victories. Yes, it's easy enough to point to those who make something of a mess of said freedoms but no one ever said that freedom and liberty were perfect, only that their presence is better than their  absence.

At which point we get this proposal:

A shake-up of the law to give extra legal rights to unmarried couples who separate is set to be backed by the Liberal Democrat conference. Supporters of the move say it is a widespread myth that cohabiting couples enjoy the same rights as if they had married. There are almost three million cohabiting couples in Britain. The Law Commission suggested six years ago that former partners who have lived together for two years should be able to make a financial claim if they break up. The amount awarded could reflect whether claimants suffered a financial loss – by giving up a job, for example – as a result of the relationship.

Last time I looked the Lib Dems were at least claiming to be something of a liberal party. So what is this illiberality? Why must cohabitation lead to financial rights? There's a perfectly good government mandated contract to take care of those issues if consenting adults should wish to use it. Called marriage and it's open to every possible legal pairing of a couple in matters sexual. Why must those who do not wish to avail themselves of this contract be corralled into something very similar just because they wish to have sex with someone for a few years?

It's a decidedly illiberal idea and goes entirely against the grain of everything that liberalism has managed to achieve in the sphere to date.