We've taken Luna over to Mike's parent's house a few times over the last few weeks. The dogs are doing well together, but it is obvious that Luna is not thrilled with Ryder. She tolerates him, but she's not interested in becoming his next best friend.
It turns out Ryder is over two years old which explains his relatively calm demeanor. However, he is a young dog who wants to play. He tries to get Luna to play by offering play bows, gentle nose nudges on her head, and happy tail wagging. For a young dog interested in finding a playmate, he is surprisingly respectful and gentle. I believe it is due to his experience growing up with an older dog in his last home.
Luna tolerates his invitations to play fairly well, but she has shown her teeth several times and given him plenty of dog body language clearly stating, "Back off! I'm not interested!". One of these days she may snap at him if pushed too much so we always supervise them. Luna has snapped at young dogs before, but she is always careful never to make contact. She just gives them a quick scary bark/snap in their direction as a warning to go away.
Last weekend, Mike and I went to a friend's wedding and we left Luna with Ryder all day. When we came back to pick her up, the report was that Luna behaved beautifully, but Ryder had to spend some time in time out when he was bugging her too much. Afterwards, both dogs settled in for a nap, but Ryder insisted that Luna stay within eyesight just in case she decided it was playtime.
I'm sorry that Ryder hasn't found a playmate in Luna, but I hope that someday they will enjoy each other's company like Amber and Luna did. I think it will just take some time for Ryder to fit in the family a little more and for Luna to accept that Ryder isn't going anywhere.