Taylor Swift's "You Belong With Me" has shades of this, with the Unlucky Childhood Friend (and borderline Stalker with a Crush) complaining about her cheerleader rival who "doesn't know your story like I do". In the video) the girlfriend is portrayed as a very typical and shallow Alpha Bitch who is defeated and humiliated by the Dogged Nice Girl and her beau's True Love. Yup, like in the Lavigne example, both are played by Taylor Swift herself, but it's still annoying.
Used literally, in Good Charlotte's "Bloody Valentine".
Standing over him, he begged me not to do
What I knew I had to do 'cause I'm so in love with you
Threatened in the obsessive-fan song "David Duchovny, Why Don't You Love Me" by Bree Sharp:
Poor, poor Meiko. Most Kaito/Miku shippers constantly call her 'abusive to Kaito' or 'slutty' because she is shipped with Kaito. And Miku doesn't get any better treatment from Kaito/Meiko fans. And Kaito/Gakupo fans are just plain Fan Dumb towards both. What makes this particularly annoying is that Vocaloid has no canon...
Len fangirls are pretty terrifying when it comes to ships involving him, but the treatment poor Rin has to go through trumps them all.
All of them are not help by the fact that by design, the Vocaloids are blank slates and their personalities are determined by the fans.
In the K-pop music industry, any mention of a celebrity dating anyone, or even just admiring someone else, can be stirred up into a 'scandal.' Some fans take their idols being in relationships that they don't approve of very, very badly.
For instance, in 2014, it was revealed that Taeyeon and Baekhyun were dating. Cue Taeyeon's Instagram and other social media being FLOODED with hateful comments ripping into her age, looks, singing ability, you name it, and even Baekhyun got some hate too.