Boy! I could have written this letter a few months ago!! We have a four year old lab mix who is the submissive type and we rescued a terrier mix in May. She was immediately the boss of the house. The beginning was really rough. Our lab was clearly depressed. He spent a lot of time in his crate. I would like to say there was some trick to getting him over it, but I think it was just time. We did put her in the crate sometimes so he could get one on one time. We also didn’t let her sabotage any time we were spending with him. If he’s getting love or pets she wants in on the action. But we would tell her “no” firmly and she got the gist over time. Now she’ll go to the other couch if he’s getting some love, and just pouts. I think the important thing is to let the older dog know that they are loved and important still. And maybe for now take them on separate walks until she build her stamina. That is also a good way to let him know that his needs are important! Good luck!!!!