I'm a lean guy with a fat wife, and I love it. She's over 6 inches shorter but for 10 years she has always been heavier. Currently she is almost 50lbs heavier than me, she's gone up about that much while I've gone up 20-25lbs of mostly muscle in the same time - still same pant size fron high-school. I really love thinking about sexual dimorphism, aside from bone structure, male anatomy is defined by muscle, female by fat. Take a sample of people at same height and weight and the women will have more fat. I like the complimentary idea that I'm naturally equipped with the muscle so that my mate can stay safe, comfortable, and amply well-fed. In my mind, biologically speaking, my partner being nicely fattened means she is better prepared to survive times of food scarcity, and she's ready to nourish potential offspring. My body is designed to care for her, so that's how I'm gonna use it.
[Not meaning to challenge how other people feel about bodies, gender roles etc, just how I am inclined to feel]