Fat by The Violent Femmes sort of qualifies. He’s hoping she gets unattractive.
Since I linked Big Legged Woman, this seems only fair…
Skinny Legs and All - Joe Tex
Wouldja believe that tune goes back to 1938? Here’s Mildred Bailey singing it with the Red Norvo band.
Going back to 1931, you have a British hit, *Miss Elizabeth Brown.
Tho’ I know she doesn’t look like beauties in a picture book
I’ll be broken hearted if she turns me down
Her father is a millionaire, he hasn’t got a son and heir
That’s why I want a love affair with Miss Elizabeth Brown*
Al Bowlly, Britain’s crooner of the day, sings it here, along with a bunch of his other platters.
Rosie by Jackson Browne? 
I also wanted to add Cholly by Fishbone
“I love you Cholly with your big fat body/ Oh golly Cholly you’re just chubbly wubbly wobbly”