Apart from the obvious personal commitment, marriage is a matter of great legal significance.
It bestows legal rights on any couple who enter into it in that there an automatic entitlement to inheritance which unmarried partners do not enjoy and also an exemption from Inheritance Tax in respect of assets passing in death between spouses.
It also gives property sharing rights to parties on the end of a union. Prior to Civil Partnerships for gay couples being introduced just over 10 years ago there was an inherent unfairness that gay couples could not have their relationship recognised in law.
Gay couples can now also get married as well, which is good news for them, but in fact now creates an inherent unfairness for straight couples. If they want formal, legal recognition, gay couples have two options: civil partnership or marriage. Straight couples have marriage only.
Many couples choose not to formalise their relationship by marriage. This may be for any number of reasons, such as a rejection of the historical, religious and cultural aspects of it including a perceived gender imbalance. There are some older people who have already had a long marriage which ended in death may not want to do it all again.
There are also couples who live together simply as companions or indeed siblings who have ended up sharing a home. For these people marriage is not attractive and indeed for siblings it’s not even possible!
An option for straight couples and siblings to register a civil partnership is something that should be possible. It would allow formal legal recognition to the relationship, some of which have lasted longer than many marriages and most importantly it would prevent the injustice of a surviving partner not inheriting assets on death or having to pay Inheritance Tax simply to carry in living in the same house as before.
Of course folk may not have their civil partnership cake and eat it; and any such straight civil partnerships would have to have the sharing of property upon separation just like everyone else in a marriage or civil partnership.