So, whenever my dog is in heat and wants to get pregnant, I try and breed her with other dogs and they are always angry at each other and just bark. I even made a crazy dog lady next door to try and get more dogs that my dog could mate with and it always happens. At one point, I adopted some random male dog got my dog pregnant and then put him back up for adoption.
To mate, do dogs need to interact with each other more? Or maybe even become friends? It wasn't an issue with my adopted dog.