It sounds like your husband could possibly have DID, but my suggestion would be to bring up the issues that are happening - such as losing time or not being able to remember what happened - as the challenges a therapist could help with, as opposed to trying to get him to get rid of or integrate all the people in the system. It would also be important to go to a professional who is experienced and up to date on plural and DID treatment/issues. Not every therapist or psychiatrist is qualified.
He has at least four other people in his head with individual identies and likes and dislikes, I’m at college for most of the year and helping with my little siblings this summer so we don’t live together but there will be days where he won’t talk to me until it’s dark out and tell me that he doesn’t know what happened, he just found himself sitting in his room, he doesn’t know if he’s gotten up or if he’s been asleep or what, there’s times where he’s “spacy” and just loses time for hours