1. A bro who was shunned or has otherwise dissociated from a group of what he thought was bros, but turned out to be douches, leaving himself to be a bro without bros.
2. A bro who is new to the area and has yet to find other bros to bro it up with.
Dude 1: That guy seems super chill, why doesn't he have any bros?
Dude 2: Bro, he's a brorphan; his former "bros" all took turns with his girl behind his back.
Dude 1: Ouch...Hey, let's bro it up with him a little to cheer him up.