Gaining

Thats a tough one: You need to find a way to uncover her issue! Try a change of pace thing, like a romantic getaway.

In my past experiences every time my wife gained a good amount of weight, She was definitely more sexual and had a softer/sweeter easy going flow about her. Every time she gains weight I can't keep my eyes and hands off of her and she is so much more receptive to my enthusiasm, that is until she gains to much and then she turns grumpy ans says she is a fat cow and needs to go on a diet! Thats where the frustration begins.

I hope you get it figured out so you both can enjoy all her new soft Lbs.

That her sex drive dropped off as she gained does not mean it was because she gained......anymore than wedding rings cause a loss of sex drive, no matter what the comedians say.

Is she depressed, have health issues, lack of time or energy, maybe not feeling emotional closeness, went on or off medication of whatever sort..... Don't just look at the most visible change. After all, if she went to a doctor about it, and doc said "you got fat; lose weight". You wouldn't be happy with the analysis.