Political polarization has transcended political arenas, influencing personal decisions. While such biases are often ascribed to out-group animosity, a person’s “party tag” may act as a proxy for other characteristics, overstating partisanship’s role in private life. To explore this, we focus on online dating, using a conjoint experiment with 3,000 UK participants to isolate the effect of partisanship from other traits. Our findings indicate that the influence of partisanship is on par with conventional criteria like physical appearance, yet tolerance for opposing views plays an even stronger role. We also find imporant partisan asymmetries: both groups favour co-partisans, but Labour supporters are twice as likely to do so. Counter-stereotypic profiles reduce bias among Conservatives but heighten it among Labour supporters.