Hi! We're new dog owners having had our female black lab for the last five months (she's 10 months old now and was spayed). Today, with no advance notice, our neighbor came over with his adult chesapeake bay retriever. Our dog was scared at first (hair on end, barking) but seemed to get used to him somewhat after a few minutes. She was still running away from him mostly but went up to him a few times as well. When his dog started mounting our lab she was clearly trying to get away. I said something and we separated them. My neighbor went on to say it's normal/natural, that his dog hasn't been neutered and that she would probably bite him a bit but that our dog would "get used to it." His dog tried to mount her again and I said I wasn't comfortable with that and we separated them again and they left shortly afterwards. It seemed crazy to me that he would just bring his dog over and expect me to let his dog mount ours like that. Is this normal? Is she safe? I've been watching different dog training channels on youtube and it didn't seem right to me but I don't really know how to even search for a situation like this. Any advice or links to information would be much appreciated. Thanks!