This is a tough one, in my opinion.
I seem to be doing it both ways here. Neither is perfect.
On the one hand, my "house chicken," a single chick, was given to me last fall. She was too small to go out with the others, then it was too cold by the time she was old enough and feathered out. At almost a year old, she spends nights in a large dog crate in the house and makes field trips outdoors during the day. (Yes, she will have to transition outdoors come winter when moving indoors and outdoors would be too much temperature change. She will have a private coop then. And, yes, I do spoil my chickens.)
Although she loves to hunt for bugs, forage for greens and dust bathe, Dot doesn't have any real chicken friends (most of my girls hang out with the hens they grew up with or their roommates from the various coops). Sometimes, she dust bathes near the others, but she doesn't have a "flock." Even Lottie chases her.
Lottie is the bottom hen in the pecking order and lives in my avatar coop. She NEVER has feathers on her butt. The girls free range during the day, and she hangs out with some of her coop mates then., I guess chasing Dottie off gives her some sense of status.
It's hard to watch a hen get bullied. But Lottie willingly hops into the coop at night with her tormentors, uses the nest boxes in that coop even though there are other coops open where she go lay. I've considered trying to work her into a different coop, but she seems to accept her position. The pecking order seems to be much harder on me than on her.
If your girl can see the others, maybe she isn't lonely. But I think she will always be the hen with the least status with them. I can't argue against getting more chickens (properly quarantined, I NEVER object to more chickens!!). but I don't know that it would solve the problem.
In other words, I can't really offer advice, only examples. Good luck finding a workable solution.
