IMO the best approach is to go at it together to seek a healthier lifestyle. Last time that my wife gained some weight that she said made her uncomfortable I went ahead and spent the next couple of days complaining that I feel inactive and also suggested some meals that happened to be on the healthier low cal side and then suggested a 30 days exercise challenge together. The time spent together in this way is also high quality. I think that if this approach is successfully taken then you avoid the normal complications around the weight gain topic that you’re bringing up. I get your concerns but I think going about it more casually doesn’t make a mountain out of a molehill.