he should practice making conversation. THe truth is you can’t be so quiet in a marriage process. Even after being married, you can’t just be quiet, it’s weird. I am not saying you have to gab for hours but you have to communicate even a bit.
He should write down some questions, make a list and practice in the mirror or to a voice recorder.
I dont’ think he will find someone if he cannot have the interest in a person to have a conversation, even just 10 or 15 minutes.
I would say he hasn’t developed socially so now is the time.
ALso if he dates someone, he should tell her this issue maybe on the first or second date. SHe might be able to help.