>>528007492
>>528007679
This
Being direct, explaining clearly, and not being condescending are the best ways to get a point across to someone who has trouble with social cues and functions

Phrasing it in a way that isn't construed as a personal attack (even if you don't mean it to be) is super important as well, as there's a high likelyhood they've been through this kind of thing from people who handled it much worse.