Extreme obesity

To watch as my partner is slowly losing mobility and the increase dependent on me is a huge turn on

Well it depends, mostly a turn on as long as they don’t effect your everyday life 😊

Seeing my new GF struggle to get up stairs really turns me on. We both know she is headed towards limited mobility.

The limitations are a huge a turn on for me and just ignite the carer side of my kink. Can't tie your shoes, let me help you with that. Having trouble reaching something? You just hang out and relax, I'll get it for you. Can't fit into the booth at the buffet and having some feels? It's okay, babe, they should be able to accommodate their best customers, you stay and I'll get you something to eat before I go talk to the manager. Don't want to walk but still want want come with? they make scooters for that, and here's a snack. Just mentally exhausted from the idea of having to feed yourself? I'll feed you.

Absolutely. Sometimes it feels like I notice every increment of things getting more difficult, and I still have a pretty far way to go before things get really limited.

Like not being able to sit down to put my shoes on anymore, I have to prop my foot up on a bench. Or when I have to work up a little momentum to get out of bed or off the couch. Knowing that it's not normal to struggle with these things gets me very flustered.

Watching a big girl struggle as she does things as a result of her gluttony is a huge turn-on!

My wife's younger sister has put on >100 lbs (which she hates) over the last year. She's so spoiled. When she comes to visit, she barks orders and I fetch nearly everything for her. She absolutely loves this and even uses me as an example to make her bf (possible closet FA) cater to her! Granted I did a lot for her when she was slim as well, but it's even more satisfying now!

Recently she mentioned getting winded after a single flight of stairs. She used to be athletic, hates being fat, and has no concept of how one can love it despite her sister being bigger and heavier, comfortable with her size, and much stronger and more capable from regular exercise.

That self-arousal which results from the consequences of your consumption will certainly take its toll. The most dangerous aspect is that it's completely self-induced. There is no external moderating force to keep you in check.

I get aroused when the wifey continually texts me at night for specific snacks to bring to her because she's just too lazy and greedy to even get off the couch during her Netflix binges.

She used to always make the multiple trips to clean up her trash, keep the house tidy. But now the night ends and the chip bags and packaging remains sprawled across her couch area. Just too lazy and fat to care about it - she knows I'll get it in the morning.

one of the hottest physical limitations, imho, is when someone struggles to get in and out of their car/fit behind the steering wheel. I'm sure actually being that person, it must be a gargantuan pain in the ass, but godDAMN is it enjoyable to watch. The latest and most prime example I've found is this clip here by "AmIFatYet?"
Guy can barely move without his belly honking the horn

"do you find the physical limitations of weight gain a turn on or a turn off?".

It's a turn on - in fact, it's the point - and the fact that it's now difficult to move or sit upright does help. But it's accompanied by certain problems (esp to my liver and kidneys) and now accompanied by sleep problems, so this is not easy. I ike the theory, but I need help overcoming the practical problems and I can't do it on my own.