You come upstairs and notice your GF standing in front of the mirror, wearing a SUPER TIGHT shirt and looking at her belly with a frown on her face. Your heart skips a beat because you think she is going to complain about how fat she's gotten, but to your delight she does the opposite.
She starts talking about how she isn't looking round enough and needs to become rounder immediately. She then sends you off to buy her a HEAVY meal. When you return she delightfully scarfs it down, while you watch, until her belly is looking niiiiiiiiiiiiiice and round, just like she wanted. All the while she is rubbing her belly, moaning in delight and breathing heavy.
Her belly became incredibly round and you are practically drooling at the sight. She then she stands and shows you the beautiful aftermath of her voracious appetite and round pursuit.