[Help]Is my dog depressed or is he just a lazy boy?

Hi!

I have a lovely Grand Basset Griffon Vendeen, 2 y/o. He's way too big, about 9 inches too high. He's always been quite lazy, sleeping for most of the day but loving play time and long walks. On a regular day, both me and my girlfriend work and he's alone during the day. He can go outside all day. We have quite a large yard for him to run in, as well. Twice a week she's home early, and once a week he gets a playmate for 3-4 hours during the day. This has always been the case.

In the weekend we make sure we spend a lot of time with him, or when we can't he's with friends who have a dog and they play all day.

We always make sure he has enough toys and a huge bone to chew on every day, which he seems to enjoy.

Now I'm wondering, is he okay with all this? We make sure to spend a LOT of time walking him during the morning to tire him out, and go out to the park every day for a ~3 mile walk. When we get back, he's absolutely battered and takes a nap. I have no exact reason to think he's depressed but I just want to make sure he's fine. He eats irregularly, and has done so for about a year. Sometimes he eats both of his food trays, sometimes barely one, but he doesn't lose weight or gain any. That seems solid as well.

I hope reddit can ease my mind.