gooddaytoday saidOne of my peripheral friends' new bf recently became part of our group.
And what does your peripheral friend's instincts tell him about his new BF? Have you asked your friend? And as far as "finding him... sitting alone at a bar" I'm not sure why that's significant. I've found decent guys sitting alone, as guys have found me.
When I first met my present partner I sensed the wariness of his friends, could almost see them "circling the wagons" around him. Who was this stranger (me), was I worthy of their friend, would I hurt him, take advantage of him? In a way I was pleased & impressed he had such loyal & protective friends, that I interpreted as the favorable sign of a good man much loved & respected, as he indeed is.
But now I had a challenge: I knew I had to win over his friends, as well as his very close Italian family, if I was gonna win him over, too. And it wasn't the first time, I had done the same with past BFs and with my late partner.
It will be interesting to see if your friend's new BF makes overtures to your group. And I hope you'll be open-minded and give him a chance. Cautious, yes, but not prejudiced, and not programming him to fail. And beware your own jealousy & selfish interests, make sure you understand your own true personal agenda in this.
As for me, I did win over his family & friends. His sister calls me her brother, and his older brother & I have become great friends. And my partner claims his friends now like me more than him. Not true, of course, a bit of ironic hyperbole. (Though my nickname with them is Saint Robert, they in turn now joking that no one but a saint could live with him, having gone from shielding him from me, to giving me total custody - LOL!)
You may be overreacting, and I'd give this some more time. And even if your friend does get burned, I presume he's as youthful as you, and can chalk this up to a learning experience. He's your friend, not your son.