How old is she? You said she was "tormented" by the other dogs -- as in, literally?
That could surely impress things on her.
Doesn't sound like you've found a right match of a playmate for her, but maybe she just doesn't enjoy the company of other dogs? Not all dogs do. I own two that do not care to play with other dogs and one that does.
I'm wondering about her being muzzled... ? Were you worried she'd attack or ?? Is there a history of anything behind that?
Does she enjoy playing ball or anything with you
? I mean, is this a matter of her not playing *anything* or not wanting to play with others? On that note, a toy between two stranger dogs is likely not a good idea, anyway.
GSD's play rough. Mine is not pb, but he plays like he is. But you can tell if you are around it. A nip on the butt from behind doesn't *really* sound like "play."
As far as guys, exposure is key. Without knowing her age/history, I can't say much on how I'd approach that. My youngest was once reactive to people with darker skin, because he hadn't been exposed to it. Over time and socialization to all kinds of people, we've come a long way. It required going all over the place, sitting at the park, going to Petco, going here, going there, the guy at the McDonald's drive thru (I don't even eat fast food!), the girl at the coffee place drive thru (I don't drink coffee!), the convenience store, the checker person at the drive thru car wash... on and on... to let him see every possible type of human being. A guy with a hat. A girl with huge hair. Someone wearing a hoodie over their head. Haha, you get the idea. Exposure is king. But slow. Never more than they can be distracted from. Ie, at one point the car wash drive thru attendant got Bails in a little fit. So I went back and treated him while we were in the line. Treated him as we moved up in line. He saw the guy out there. Treated again. As I talked to the guy, I was treating him. We can now go thru any drive thru without issue. (FWIW, I ate the dang french fries, but poured out the coffee
) But it took some work. May be the same with a male for you. Easy and slow. Treats and distraction.
Sorry to ramble.