This paper studies the social networks and feelings of social loneliness of a group of migrants that, because of their European origins and their mixed relations with a native partner, might be easily integrating socially. The data are a sample of 237 (first-generation) European migrants with a native partner living in Belgium, drawn from the EUMARR study on binational couples. First, their social networks and feelings of loneliness are compared to those of natives in a uninational partnership. Second, structural equation modelling is performed to study the effect of various characteristics of local and transnational networks of family and friends (such as size, composition and intensity of contact) on feelings of social loneliness, as well as the link with migration history. Results reveal that European migrants with a native partner experience more feelings of social loneliness than do the native population. A larger local network, with more own relatives and more (own, not met through the partner) friends, as well as more frequent contact with local friends contribute to lower levels of social loneliness. Transnational contact and the share of natives in the local network have no impact. The findings contribute to a better understanding of the social life of European migrants and show how, even with a native partner, they are still affected by the migration move in relation to feelings of social loneliness.