No matter how mightily we puny humans may try to tame the surrounding environment in conformance to our wishes, we cannot fool Mother Nature.
Sadly, all-too many of us `pon this mortal coil have lost sight of what is needed for our stewardship of it.
(https://www.rover.com/blog/cat-primordial-pouch/)
Thanks for the update photo! Dewey has a yellow star toy, without eyes though.
I had a cat that was 23lbs. Not doing that again. Oddly enough he was the sickly cat with diabetes and Asthma requiring insulin and lots of meds and he lived the longest of any so far - 15 years.
Wow, 23 lbs!
Starting with my “big brother” Alex, an indoor-slash-barn cat, all of my chonky cats have lived longest and happiest of all, even with health issues.
I don’t think that in/out has too much to do with the issue (although it might play a small part).
I’ve had two pairs of indoor only cats. First pair were brothers, nearly identical. Neither was very fat, although Charlie got a bit pudgy as he got older (15+ years).
Current pair are rescued feral kitties from the local colony; Pumpkin looks a lot like Ollie, and at almost 4 years old, is finally not looking too skinny (he’s a bit over 12 lbs). But Magic is fat; although he’s naturally a lot bigger than Pumpkin anyway; but 21 pounds is too much. (we’re pretty sure that they have different fathers; Magic’s was a Maine ■■■■).
Pumpkin is certainly the more active; although both can get the zoomies. And I can tell you, there are few things more terrifying that looking up and seeing a 21lb cat with the zoomies headed straight towards you! (he can move the sofa; WHILE I’m sitting on it)
Oh, and they both have the primordial pouch; very evident even when they were fairly small. True also of their mother, and many of the cats in the colony. I think it’s more genetics than anything else, but don’t really know.
ETA. Wow, last four letters of Ra*oon (the species of Rocky from the Beatles, and Rocket from Guardians of the Galaxy) is a bad word here.
Because that 4-letter word is also a racial slur, in some parts of the USA.
But I know you mean Maine ■■■■ - Wikipedia 
The Discourse Platform, by default, has a built-in filter which prevents spelling “Coοn,” because that term is considered offensive by more than a few people in These United States.
ETA: Papy beat me to the explanation for the filter:
Missed it by that much 
Yeah, I know it can be a slur. Just frustrating that a few jerks can destroy things for the rest of us.
Nail, meet sledgehammer.
I had a love like yours, also a tabby. When we lost him I found a quote from Anatole France that summed it up …“Until one has loved an animal, one’s heart remains half open”… ( or thereabouts)
Oh my goodness! 
Losing them is just like a person (almost).
Depends on the person.
I have heard that ginger (orange) cats are more loving; although I’ve also heard speculation that this is more a factor of male cats being more loving, and about 80% of gingers are male.
I’ve also heard that rescued feral kitties become very attached.
So when you rescue a ginger, seems that a result like Ollie or Pumpkin (who stays glued to Nisha) is the likely result. Which just makes it all the better.
I (we) have had many cats over the years, gingers included. With a few exceptions, the male cats have always been more loving than the females.
The cat I have now, Buzzy, is a Siamese-Tabby mix and he is perhaps the most clingy and loving cat I’ve ever had.
I also have a 16 year-old ginger/white long-haired cat who is not doing well. 
I haven’t spoken much about him because of his condition. He’s a smart cat and realizes that he’s not well. He has good days and bad days and sometimes a little of both.
Of our current 5 cats, the one between the two sets of brothers is a female calico–and you know what they say about calicos. Yes, she can be nuts, but she’s my ride or die whether I like it or not and firmly believes that we run this house as equal partners above all other inmates. She wants nearly-constant nearness to me, seeks pets in hilariously communicative ways, tries to groom me if I ignore her, and so sweetly insists on invading all of my personal space. Her motto is that if we’re not breathing the same air, then it’s not cuddling!
Last night I was hollering at some kid in another room, when she perched in my lap so that we were eye-to-eye, looked at me very seriously (imagine a librarian looking at you over their glasses, like McGonagall-in-cat-form), and put one paw on my shoulder. Kid guffawed and said, “Mom, Lula says you need to simmer down!” 
Two other female cats over my 40+ years also stand out as exceptions, but otherwise, yes, I generally agree that male cats are more often and widely affectionate and friendly.
In my experience, when we humans realize that higher-cognition lifeforms like cats & dogs know themselves that they’re reaching the end of life upon this mortal coil, the best we puny humans can do is to make their passing HOME as painless as we possibly can.
More often than not, unless most-every single minute of their days are entirely filled with agony, following that path entails making them as comfortable as you possibly can, until the time they themselves decide that it is time to give up the ghost.
I am not a fan of euthanasia short of last resort - and when a pet one has cared for as many years as you have reaches that stage, you’re bound to know what is the RIGHT thing to do for them - just like you are bound to do at any stage of their lives.
I am so sorry your 16 year old feline friend is not doing well. It seems many of us understand how that feels. I imagine your cat has a very fine family and feels loved and cared for.
