I am so sorry you are experiencing this. It sounds as if this person has lost interest. And worse could be having affairs -- even if they are just online or text affairs and not in person. That is hurtful behavior. If you do not live with this person I would stop communicating with him and move into another phase of your life. If you do, I would seriously consider becoming platonic roommates, but ideally move out. I know after 20 years it would be very tough to take these measures. Before you do any of this you could have a non-emotional conversation about your feelings with him. I say non-emotional because a neutral tone in a conversation can help it stop from escalating and help prevent more emotional harm.