If he was able to reach out to you to write these? Then it's likely he could have done so before, if he needed someone to be there for him. [It's not the same as being kidnapped to torture island. As far as they know, Raf could have called or emailed at literally any time.]

Believe me- I'm not going to tell you that you shouldn't worry, and I know that guilt goes hand in hand with that so easily. But whatever has happened to him isn't your fault. And if he needs help? We'll do everything we can to help him. [She takes Buffy's hand and gives it a squeeze.] Together.