Well, do you really need to be married? I mean, I can see how you would take it as some sort of vague assurance that the relationship is "official", but it sounds like your feelings are already pretty well-established and being married isn't really needed. I'm also not quite understanding the terms he has. I don't know why it would necessarily matter that your son is living with you at the moment? Maybe he wants to feel more emotionally invested in the family aspect?