Allow me to be blunt: you’re still suffering the symptoms of depression. I’m not a psychiatrist but you likely have what I’d think of as “situational depression” (as opposed to ingrained depression). Once you either fix the cause (loneliness) or adapt to it, the depression will lift.
I think it’s worth saying that you need to learn how to be comfortable in your own company. That’s the easy bit, the hard part is figuring out how. I don’t think there’s a trick you can do, you need to put in some work. Maybe take your dog walking to more remote places than just a dog park? I guess if you’re in America this might be more difficult but are there any green spaces within a few hours drive you can spend the weekend at?
