S.T.
aw, that's so tough. i remember dealing with this several times myself as a child, and then my boys experiencing it too.
the temptation is to try and fix it, to jolly them out of it, to persuade them not to be sad. it's hard seeing our kids sad.
but in a weird way, trying to cheer 'em up also minimizes their emotions. so do be careful not to do that.
i think the best things to do are to listen to him and not try to say 'but....' with silver linings. if you need to respond at all, validate him. 'it sure sounds as if this is making you really sad. i'm sorry. it's hard to have a friend move away.' and then, if HE seems to want to more, ask him what ways he can think of to stay in touch.
and it's also okay to store up a few treats to help him cope when the sadness sweeps over him. a favorite video with treats, a trip to a park, an extra bedtime story.
you can't and shouldn't sweep away the sorrow. help him learn through undergoing the experience that it does get better with time. there's no way to internalize that through words, only by chugging through it.
khairete
S.