My partner has been married twice. I have never married. We have been together 16 years. Even if we wanted to get married, we couldn't afford it. The main problem that we may face potentially is that I own the house. If I were to die without leaving a will, my partner would have no claim to the house. She would be homeless. Even though she has paid for the majority of the renovations and furnishings.
@Jacko1971 do it asap! My brother died at 43 in a car accident. He had 3 kids. Two from first wife, and a 3 year old from second wife. He had no will. It was an ordeal.