@kaia so she's not ignoring him.
Straight up just ask. Literally. No subtext stuff, that gets confused.
Weave in the coping strategies that have been mentioned above when out on the date. Things can flip and change if overstimulated, so the friend will have to not take it personally and help autist if that happens. But not help. Help by.... The autist will know what to do, they have to helo facilitate that. 👍