She is unhappy about the weight and not delusional.
There are a few things going on in with this one specific couple. For instance, the hubby has disappointed her in other major ways, so I think she's like, "you turned out to be WAY less than my expectations, so deal with this extra weight."
Another thing, she holds on to pics of her thinner days and constantly talks about her "fine" days. But she is only 34 and so beautiful, she can lose it and enjoy today but she's so stuck in her 20s.
Lastly, she is a great cook and stuck in her ways about making minor changes to her diet and substituting certain ingredients, managing portion control, and regular exercise.
As for the marriage vows, is it realistic to expect the spouse to not have human reactions to our negative behaviors? A spouse's attraction will change if the other abuses drugs or alcohol? So if you let food blow you up, why is it a surprise that the spouse will have issues with it? The other spouse is put in a position that they are being insensitive if s/he says something but also gets blamed for dishonesty if s/he doesn't say anything. Resentment grows, causes wandering eyes, etc....
Marriage is a love affair and attraction is an important element. Isn't it a responsibility on both person's part to nurture that aspect? Maybe not in a shallow way, but in a way to preserve the spark.