The new girlfriend is clearly burning her too. Unlike some here, I actually don't think the new girlfriend is younger or skinnier than a Becky, because if she was I truly think she'd have mentioned that during one of her "replacement wife" rants, much like how she says his new girlfriend is less mentally ill. She'd get a lot of sympathy if she broke out the "my ex left me for a younger/thinner woman" card, so there's a reason she's not using it. Daniel has likely gone for a single mom who is either similar in age or weight or even older/heavier than Becky, and that stings her even more because it means that she wasn't good enough because of who she is as a person, rather than something like not being a 23 year old childless waif.