Yes, functional relationships tend towards maintaining equilibrium in a manner that isn't just tit-for-tat. An interesting study I once read indicated that on average relationships can only withstand around three months of extreme disequilibrium before starting to come apart. The odd thing is that it is frequently the lower functioning partner who ends the relationship due to the stress of disequilibrium.I wouldn't be surprised if she'd start to apply similar positive patterns in other, unrelated areas!
Your comment caused me to consider whether somebody might be motivated towards becoming more frugal if/when their more frugal partner became more fit. That's a tough one to calculate/empath. In the benighted innocence of my youth, I believed that "being frugal" was one of the hallmarks of "being a good wife" and couldn't understand why I didn't get more appreciation for my efforts. Pretty much akin to the not-so-positive feedback you received for losing weight, but widely swinging with the extent to which one's partner positively or negatively identifies as an Earner/Provider. It finally clicked with me when I was describing the relationship between my spendthrift mother and frugal father to a BF, and he laughed and said "She just wanted the kind of man who would say, 'It's Friday night, baby. Put that new red dress on, we're going to town.'"