Wilfred was not a perfect show, but that was a perfect ending for what it was.

Turns out Ryan has not one, but two, batshit crazy parents. Stands to reason he'd be batshit as well. Projects this personality onto a real dog, and then the real dog dies, yet comes back, finally answering Ryan's question about what Wilfred is - all in his mind. It always had to be that. Anything else would have been ridiculous. I thought it was great when his hot ass sister asked what would make him happy, and he decided to just embrace his mental illness.

Some other observations:
That image of the real Wilfred lying there at the end of part one is about the saddest image ever, especially since nearly everyone has lived it.

"Many Rivers to Cross" is such a beautiful song. Perfect choice for a sad montage, but the montage itself didn't work. I think the main problem was there was dialogue.

Mimi Rogers does a dynamite Mary Steenbergen, but I really wish she and Dwight Yoakum would have been able to see their roles through. In a show about an elaborate hallucination, characters' changing appearances were unfortunate.

I liked the full circle suicide attempt and especially the line, "Good-bye girl next door."

I have one friend who watches this show, so it's a fairly lonely good-bye, but I'm glad I get to have it.

I liked the ending too, it did a better job wrapping up than better regarded series before it has.
I was a little surprised Wilfred death was not in the last episode. We already had a lot of resolution (loved the "heaven" scene and the last basement scene) by time the camera pulled back for the overhead shot with Ryan & the real dog. It would have been a heck of a dark way to finish but at the same time it would have fit.
The true finale felt a little forced in trying to explain away all the cult stuff and that Ryan's father was not his biological father. It also felt much more sunny & optimistic with Wilfred coming back to Ryan but Ryan accepting and aware that he was Ryan's conscience/psyche as an anthropomorphism. But in fairness once Ryan understood that version Wilfred wasn't real there was no reason he could not come back as an imaginary friend. I do think they overdid the beach metaphor replacing the dark basement with their interactions and a "Ryan lived happily ever after" closing. The montage of Ryan with real Wilfred showed he's much more delusional for it to end that way.
I don't know what to think of the whole Jenna character. On one hand she was needed as the golden ideal for Ryan and a plot device for him to meet Wilfred but in the end she really didn't do much for the series run. She briefly got with Ryan to fulfill that fantasy but left him to go back to douchebro. And we all know in real life the guy does not always get the girl.
All in all I'd say the show was inconsistently good but in the end I'm happy to have watched it through.

I think I would have preferred if the last episode didn't happen and in the next to last episode, Ryan ran home (instead of the beach) and committed suicide. The last episode explanation was Fight Clubby to me, but it's exactly what I thought it was the whole time. I liked seeing Wilfred the dog - that was the first time since Season 1, right? I'm glad he didn't end up with Jenna as their romance felt very rushed to me. Has anyone involved with the show confirmed that anything post-milkshake-nap actually happened and all of that wasn't part of a heaven / hell / purgatory sequence?