Adapted from a recent online discussion:
I see your point [that it's unfair for someone to gain weight or otherwise change drastically after getting engaged]. However, say she gained weight after the wedding, due to children, or a health issue, etc. Would he plan to divorce her then? What if he goes bald and isn't so HOT himself? Appearances change; even if you marry a hottie, they won't always stay that way. This guy seemed to only care that she was HOT.
Re: Honey, You Do Look Fat
No no no! I almost went into this, so I'm glad you brought it up.
The things you talk about are ravages of time, or twists of fate, or byproducts of good and mutual decisions. That makes them very different from gaining weight the moment the ring's in the bag. That's why I focused on bad faith, not looks. Remember, Bride apparently is not treating a 45-pound gain as a problem, with her health or otherwise.
People will age, and they will thicken in the middle and lose their hair and teeth and all that great stuff. But if they represent themselves honestly to each other from the very beginning, then any attraction they generate will be more likely to be based in that honesty, vs. the lie of a carefully managed, and ultimately false, image.
To extend the argument with one of your examples: If he loses his hair but generally takes as good care of himself as he always did, and if she gets poochy in the belly from having a couple of kids but generally takes as good care of herself as she always did, then these two will not be facing anywhere near the same challenge to attraction that this groom-to-be is right now.
He just figured out that what he thought was hot was all just an act. Of course he's resentful.
And even if you disagree with everything I've argued, or find both the groom and me offensive, there's still the matter of his not finding his bride attractive anymore. Even if he's shallower than a sound bite, he's still got to speak the truth.