This article analyses the shifting media visibilities of femcels: women who self-identify as being involuntary celibate. It first considers the ‘original’ femcel community which emerged on Reddit in 2018, and which was based on often-despairing, even nihilistic, text-based discussion. It then considers the more recent shift to ‘femcelcore’: a social media aesthetic or ‘vibe’, communicated through short, apparently ironic videos on TikTok. We contextualise ‘original’ femceldom within the ‘femosphere’, a complex ecology of female-centric online communities that mirrors the deeply fatalistic, gender-essentialist, ‘red-pilled’ logics of the manosphere, and we situate ‘femcelcore’ within recent histories and aesthetics of ‘sad girl’ culture. Despite their differences, both iterations of mediated femceldom ostensibly reject patriarchal notions of feminine ‘perfection’; they seem to offer a critique of neoliberal feminism, and to comprise a potentially feminist online community, and as such, we consider whether this phenomenon may signal a radical break with the hegemonic postfeminism of recent decades. However, we argue that both iterations of femceldom ultimately provide a weak and highly problematic basis for collective feminism. Drawing on Robyn Marasco’s concept of ‘womanly nihilism’ we argue that, rather than pursuing a feminism of solidarity and collective strength, these mediated femceldoms are rooted in logics of pain and fatalism; they mobilise strategies of self-numbing, dissociation and irony, coupled with the rejection of social hope. They signify not a collective feminist movement, but a fatalistic, dissociative, ‘anti-hope’ retreat from transformative politics, and a turn to the individualising dynamics of TikTok ‘vibes’. Building on Asa Seresin’s notion of ‘heteropessimism’, we introduce the concept of ‘heteronihilism’ to make sense of the widespread mood of ‘giving up’ that is increasingly entwined with, and expressed through, the radicalisation of negative heterosexual experience. We therefore introduce a new theoretical lens for analysing the politics of gender, sexuality and popular media, in a context of a growing and complex backlash against ‘liberal feminism’.