Using a four‐person email negotiation on a fictitious house‐sale as the context, this study explores the effects of (1) familiarity and similarity manipulations on agent‐agent relationships, and (2) the emotional attachments that novice agents and principals form and maintain over the course of a single negotiation. Results show that only agent‐agent pairs receiving both manipulations (similarity and familiarity) were uniquely more successful in achieving an agreement, and that positive feelings for novice agents begin aligned with the principal and end aligned with the other agent. This demonstrates that relationship‐building in the online environment may be easier for some partnerships than for others, and that the dual‐loyalty conflict facing agents seems to encourage one partnership being preferred to the other at any one point in time. Implications for theory and for email negotiations are discussed.