Just be there for him. Let him vent. Let him take time to recover from it. It's better for them to be friends if one doesn't want to date, though there may be some awkwardness between them. Just kinda be aware of that.
tell them both ''you tried-you shared you were honest--you have the experience that makes you stronger...this is life this is how we do it ...and then there is always tomorrow''!
HOPE IT WORKS ..IF NOT maybe try not to worry about their feelings and provoke them to not put you in the middle by telling you about what they are doing...? idk hun...tough call...
The one that did the rejecting shouldn't feel bad. They were perfectly within their rights. The one who got rejected, it's not the end of the world. Maybe they should spend some time apart for a while, so the awkwardness can blow over.
geez he better get some hide on him or he will never survive this world its full of rejection
First of this is not drama honestly. Your friend who said no to the guy was just being true to herself. He will get over it eventually.
Stay out of it