Erop of eronder is a powerful Dutch idiom that literally means "on it or under it". It's the perfect equivalent of the English expressions "make or break" or "sink or swim".
In this song, it's used to describe an ultimatum in a relationship that's at a crossroads. The singer declares it's time for a final decision: either commit fully or break up. This phrase perfectly captures the song's high-stakes, all-or-nothing feeling.
Have you ever been in a relationship where you just don't know where you stand? Pommelien Thijs gets it. In "Erop Of Eronder," she's fed up with the uncertainty. It all starts when she reads an article online—even though she says, "normaal geloof ik niks van het internet" (normally I don't believe anything from the internet)—about the signs of "half-love." This gets her thinking about her own situation.
She's at her breaking point. Every time she asks her partner what they want, they give her silence and leave things open-ended. So, she lays down an ultimatum in the chorus: "Het is erop of eronder, nu of nooit" (It's do or die, now or never). She's done wasting time and demands clarity, asking the big question: "Is het beter hier of beter dat je gaat?" (Is it better here or better that you go?). It's a powerful demand for a real commitment: give her everything, or nothing at all.