He doesn't like larger dogs, Paige, and continually put himself in danger by picking fights with Dakota. I had to keep Ripley separated from all the BCs (though he would play with Eve occasionally when she was a puppy, he didn't like her once she got bigger) and because he wasn't reliably house trained, that meant that he was spending a lot of time in a crate or ex-pen when he couldn't be the center of our attention. While the crates were big enough for a great dane and the ex-pen was outside where he could get fresh air and stimulation, he really wanted to be the center of everyone's attention, and that couldn't happen when he would start fights with Dakota (who could've killed him with one chomp) and bully Eve. But most of all I just didn't think he was living his life to the fullest. He wasn't an easy dog to rehome because his personality and quirks aren't something that most people would really enjoy. But Sheila is great, Ripley adores her and she dotes on him and pampers him more than I ever could've hoped, and loves him for exactly the dog he is (something i thought only my mom and I were capable of, lol)
If anything ever happens and she can't keep him, she's promised he'll come back to me. But I don't think she's going to be parting with him very soon.