Thanks Casa, you eased my mind on this. My partner and I also inclined to just show the salaries.
We have a joint tenancy agreement for the same flat for over two years, joint electricity bills, an odd council tax bill + loads of bills and documents in either my name or his, with the same address. We are also both named drivers (he as a spouse/partner) in the car insurance for the car we bought in my name. If this is not commitment, I don't know what is
Also, how necessary, in practice, are 'cover letters' or personal statements? The guidance does not really require them and the form asks all the relevant questions. The idea of writing a mushy statement just makes me cringe and I would think that having a cover letter, when everything else is in order, look a bit like 'trying too hard'.