小三落伍了闺蜜走你
[xiăo sān luò wŭ le guī mì zŏu nĭ]
The term 'Xiao San' (third party in a relationship) indicates a cheating scenario in a love story while this whole sentence means 'Being a mistress is out-of-date; now besties go all the way'. This is likely used humorously or sarcastically, showing disdain towards being unfaithful but embracing a loyal friendship.