I am a lot older than you. . my DH also said he never wanted to get married and we didnt for 13 years.. .we had our own houses , but as our ( separate,) children got older he changed and we did marry.. it wasnt an issue I never pushed him..
But i had said I would never buy a house or live f/t with someone i wasnt married to and I stuck to it .( I was well and truly **ed after my 1st marriage broke up in that respect and was not going to let mine and my sons roof be jeopardised again ) .
But the thinghere for you OP, is if he dies in 20 odd years (or longer hopefully) his kids can have you out of what has been your home , just like that . no comeback..
We still have two houses (although we live together ) but they are now in the same pot. Our wills make provision for the kids but only after we are both dead.. (yes the survivor can change this but i wouldnt and i trust him not to either).
But the fact is by being married.. I can not be forced out of the home I have lived in so long when I am an old woman, should Dh go first.. It is that which is so important..
If he doesnt see that , then he doesnt have your 'Joint Enterprise' at heart..(let alone have a care for your well being, as th eperson he is supposed to love) The kids wont miss out , they will just have to wait to inherit , just as they would have done if his wife was stil alive ..