A preterm birth and subsequent hospitalization of an infant at a neonatal unit (NU) implies an extraordinary life situation for mothers, in which the maternal role and breastfeeding begin and evolve in a medical and unfamiliar setting. Descriptions of how women experience “becoming a mother” and breastfeeding in such a situation are sparse and this question was addressed in the present study. In this qualitative study, inspired by the grounded theory approach, in-depth interviews were conducted with 25 mothers whose very preterm infants had been cared for in seven NUs in Sweden. Findings indicated the importance of quality in social bonds with the infant, father, staff and other mothers at the NU, for “becoming mothers” and experiencing mutually satisfying breastfeeding. Three themes comprised a structure for descriptions of experiences, social bonds and mediated emotions: (1) ‘loss’ of the infant and the emotional chaos—“putting life on hold”; (2) separation—a sign of being unimportant as a person and mother; and (3) critical aspects of becoming more than a physical mother. The qualities were described as trustful or distrustful, characterized by accompanying feelings of pride/trust or shame/distrust. Social bonds were affected not only by the interpersonal interplay but also by the public environment and care routines. In conclusion, the contextual setting and distrustful social bonds impaired the ability to “become mothers” and the sensation of reciprocity i.e. breastfeeding becoming dutiful and not mutually satisfying. As breastfeeding is an intimate interplay and a personal choice it was considered that the best breastfeeding support would seem to be provision of a favorable environment that enhances the mother's confidence in herself. The contextual setting should be modeled such as to create conditions for a trustful and reciprocal mother–infant bond.