WIBTAH for rehoming one of my dogs

We have 5 dogs, 3 pugs and 2 bernese mountain dogs. We go the pugs when we were living in apartments and wanted smaller dogs that didn't require as much walking time. When we moved to the country we have a huge backyard, fenced in. However, the hawks, bald eagles, coyotes, and bears share some of our acreage and we were afraid to leave the pugs outside unattended. So we did a bunch of research and got a bernese mountain dog. He was true to every instinct we were looking for and can puff out to the size of a bear, but is the most gentle creature with the family. Cats/dogs/kids his instincts were on point. During the summer my parents would come up with their 2 large breed dogs and the big dogs would have a field day tussling in the backyard.

When our existing berner turned 7 we prepared for getting him some support in the form of another lpd to both play with and prepare for helping him take care of the pack. We went to a different breeder for the new berner, and did not realize they had taken the line away from working dog directly toward show dog. To be clear, he is a sweetheart of a dog. Loves people, highly trainable, theres just one problem - he likes people, not other animals.

At a year and a half he is kept separate as his boredom can spin up into massive insecurity and starts tiffs. I call them tiffs because while they SOUND terrifying, none of the dogs are actually harmed beyond tuffs of tail fur and humans can break it up. When we got the dog we had a larger pack in the summer, more calm influences in the house (my daughter and parents), less stressful influences in the house (my son), and way more time. Now, it feels like we're letting everyone down to want to rehome the dog, but feel like its unfair to him. In our research they are saying he is likely a "velcro" dog, and we know the breeder sent him to us at 6 weeks old, we know he does great being the only dog and is picture perfect in public. Now though, its just hard to trust him.