Social media platforms enable like‐minded users to form online groups, interact and thereby contribute to ideological polarisation. However, online groups also polarise along a continuum of liking or affect for their group compared to other groups. We explore affective polarisation on social media and its implications for online intergroup interaction. Using social identity theory, we investigate the effects of group identification, passion, and affective polarisation on social media users' intergroup approach and avoidance tendencies. We test the research model in the context of political groups on social media. We find group identification contributes to affective polarisation by strengthening favouritism for the ingroup rather than hostility for the outgroup. Although those with greater group identification prefer to confront (approach) the opposition group on social media, the behaviour is a function of inflated feelings for the ingroup more so than animus for the outgroup. Interestingly, users with greater affective polarisation tend to shut out (avoid) the rival group on social media. Our findings imply affective polarisation contributes to group isolation that may exacerbate ideological polarisation.