[TibetanPrincess]

You need to find a mate early on that is attracted to the whole package.

So if after 20 years, one spouse ( either sex ) gains 150lb, but the other is still the same weight they were at 18. Would you expect the thinner spouse to still love the obese spouse unconditionlly? ( assuming the weight gain is not medical related ). Especially if the thin spouse made it very clear at the beginning they found obese people a turn off?

To me, the comparisons are different. I could see if one had Gynecomastia and couldn't do anything about it medically (like an obese person ). But to go on and encourage such a side effect as in breast growth journey, that's when it becomes a diferent situation and that has to do with what's in the heart.
Of course, if you have been fighting those feelings early on, the least you can do is disclose it to your potential partner (which I know is difficult), so that you can freely become yourself and that she doesn't have to be put in future situation she may resent.