That's not being a failure --- that's being wise enough to acknowledge there's a problem that you don't have the means to solve.
Buddy will find a good home. Bear in mind that sometimes dogs just don't like each other. And sometimes circumstances just aren't right for a particular dog.
My shepherd girl Lady is an example. Biscuit hated hated hated her when I adopted her from her previous owners --- but I was fortunate that I wasn't working at the time so I was able to stay here and navigate the problems, meaning things didn't boil over.
But Yogi loves Lady. In fact, Yogi loves Lady more than (ack, this feels like a sacrilege) he ever loved Biscuit --- probably because Biscuit was a very dominant dog, while Lady is submissive like Yogi. So temperamentally, they're very well matched.
Different dogs - same environment.
Biscuit's hatred for Lady was such that I even tried to find her another home, and had I been working at the time, I would have made sure she got into another home.
So long way around to say, it's wiser to acknowledge the problem and allow Buddy to go back into rescue so he can find the right home.
