"You can put all the legal agreements in place that you want, but as an unmarried couple, there is nothing to stop one person in the couple from changing those agreements without the knowledge or consent of their partner. "
Um, he can't "unsign" the cohabitation agreement. It's a signed contract, to get out of it he would have to negotiate with me. Same if I wanted to get out of it. If we split up he can't say "poo, I never meant to sign it" or "I've changed my mind" - that is the whole point of it.
He can't change the way the house is held legally from tenants in common (meaning we can each leave our share, which is actually 50% but could be any share, in our wills) to joint tenants without me knowing as we are both registered owners so he needs my permission:
www.gov.uk/joint-property-ownership/change-from-tenants-in-common-to-joint-tenants
Yes, he could write a new will, wills are [quite rightly] private, but so can a married person. That only affects a person who is expecting to inherit and then doesn't. I am not expecting to inherit.
He could cancel the life insurance I suppose but I would notice the payment wasn't going out of the joint account. Or maybe he could reassign it somewhere but, again, if that happened I am fairly sure there would be a very good case to be made for it to be reassigned to its original purpose, especially as it is paid from the joint account so I would have a say (and as it is assigned to his ex she would have to sue his estate, she couldn't sue me and if he had reassigned it to me I'd just give it to her anyway, I don't want it).
Equally he cannot change the joint account into his sole name without me knowing, banks don't do that.
Once we get power of attorney sorted out, yes, he could revoke it, as I could mine. But marriage doesn't give you 100% power of attorney over an individual's affairs anyway, you still need POA for financial matters that are not joint.
So, there are plenty of things in place to stop someone just revoking all the legal agreements if people can be bothered to work out what they need to do to get them right in the first place - which most people cannot.
In my case I have far more than him, so it was important to me to protect my share of the property and to make sure if we split up I don't lose out.
I personally think we should have pre-nups in this country and if we get married we will be having one. I am not rich by any means but he had no property equity as it went to his ex in the divorce [rightly] and I had a house with a very small mortgage I was on track to pay off by age 50. Although they are not formally recognised in the UK there is plenty of case law to rely on where they have been used as indicative of the expectations in place.
He has no interest in taking anything from me (I could pay off the mortgage now but he doesn't want me to as it would be 'unfair', for example) but I won't allow myself to be unprotected because in a split people change and are influenced by outside parties with a sudden interest in matters.
The whole story would be different if we were going to have children, which we are not, and I do understand our situation is outside the norm/average.
And I didn't put all this in place because I don't want to get married, I did it because we are not married.