It all depends on where the damage occurred and if they can prevent more, You said he knew your mother by name. If you meant he could say her name. I think that is a great sign. Loss of speech is devastating and harder to recover than walking or other physical rehab.
As soon as he is stable for a day or so he will probably be sent to rehab. That can mean anything from a convelescent facility where they offer PT for 30 minutes. three times a week to a real rehab facility where a team organizes 6–7 group and individual classes a day based on the patient’s needs. I was lucky to get the latter;
Whatever happens you are looking at a long and difficult journey, You say he is your mother’s fiance but that can mean different things today. She really needs to know if she is going to be able to be his caregiver. Thr site that helped me was strokenet.org where they have message boards for the stroke survivors and caregivers, Those people are REAL!
Things are going to change for everyone and it;s best to just accept it and live the best life possible. Of all the people (about 20) in my unit, I was the only one able to return to my job. The core of my job is my memory and mental skills and I appear to have only physical limitations. But the reality is that I don;t have the mental stamina I used to. I usually start work about 7 and by 1:30 or 2 I am mentally exhausted while prestroke I could work 12 hours standing on my head. I have arranged to have a less stressful assignment for my 5th period and then my prep period last
Even if he won’t be able to do everything he did before make him do as much as he can. When he is in rehab and afterward foster his social network. Don’t let him withdraw. Try to keep him as active as possible.