From the pattern notes:

“We know, we know, we said, “Don’t knit a sweater for your boyfriend until you have a big fat diamond.” Julie disobeyed her own sage advice and knitted this sweater for her then boyfriend, John, and it turned out to be the exception to a generally sound rule. Before she knitted it, she made him swear that if he broke up with her, he’d give the sweater back. John thought that was a pretty good deal, if he ever did want to break up with her, he reasoned, he could just hand her the sweater instead of worrying about throw to let her down easy. Luckily for everyone, he handed her a ring instead.“