Am I making my dog depressed?

About a month ago my senior dog died. He was with me for many years and lived a long, happy life. I always felt like we were two parts of the same soul.

I also have a 15 months old staffy mix. We take long walks every day, he has lots of toys and stuff to chew on and generally I engage with him almost every time he initiates play. We also train commands and stuff. He's a very sweet boy and I love him very much.

That said, I'm still very deep in my grief and as soneone with fragile mental health, I've been very depressed since the loss of my dog. I'm sleeping most of the time where I'm not taking care of my staffy and the little I'm awake and not actively taking care of him, I'm kind of just staring into the void.

I've noticed since the loss of my dog, my staffy has been getting into trouble a lot less and initiating play less. If this happened before the loss of my dog, I would have assumed training was starting to pay off and he was getting better at settling. But the timing makes me wonder if my depression is affecting him and if so, what do I do?

He's eating, drinking, pooping, walking and engaging fine. He was recently at the vet who checked him over.

Also, he didn't have much of a relationship with my senior dog. My senior tolerated him at best so he didn't lose a playmate or cuddle buddy or anything like that.