I realize this after seeing a Tumblr post bringing up this topic, which they settle by making an original character for their fanfic
Does he have a civilian friend in canon? I mean friends friends. Not a professional friend/employee like Lucius. Someone he can hang out with that is not Clark.
The first thought is Commissioner Gordon in the Golden Age where he regularly hangs out, but even then he's in his lazy playboy billionaire persona.
Then of course Harvey Dent before Two-Face.
Tommy Elliot showed up in the book where he became a villain, and we don't see them until they start hanging out.
I thought he's about to be friends with Lincoln March, but nope, villain again.
Leslie Thompkins... he doesn't hang out with her. I kinda want a hangout peer.
The story pattern that his friends turn to villainy or death fits the theme of Batman is always lonely that DC wants to sell, but it doesn't always have to be that way.
The problem of course is his Brucie Playboy persona where that means he's gonna pretend to hang out with suckups, and even if he's not in Brucie mode, his own character as Batman doesn't allow people outside to get close, either to keep his secret or keep them safe.