Lollee, if unmarried partners make a will as security, surely wills can be changed and leave one partner with nothing.
I have a married friend who has a wealthy husband with dementure, he has just changed his will so to protect herself she is having to divorce him. Everything is in his name, the joint account has little money in it, at least she can get something from a divorce, it's sad they have been together for 30 yrs and he means to leave her nothing!. His reasoning is " I picked her up in a bar, I have given her a good life,(true till recently) she can go back to the bar".
She cannot get power of attorney, he is just belligerent and won't see reason, so even if you are married it might not be plain sailing.