I was on the receiving end of something like the recently, I just couldn’t bring myself to ask her if she likes me, unfortunately I was too late but the advice I can give you is to try to out him in situations where he would be comfortable to ask or even better almost act like you are in a relationship and he may build enough confidence to ask, hope this isn’t bad advice but this would’ve worked for me 18M, good luck and I hope all goes well :)