Merchanter's Luck (Alliance-Union Universe) (1982)

Sandor cannot keep a freighter viable entirely by himself, while Allison comes from a large shipboard family with its own expectations. Cherryh makes the arrival of other people both an opportunity and a threat to a captain used to guarding everything. Trade, fatigue and who is entitled to give an order keep the relationship practical. A relatively compact, tense choice for readers interested in how trust makes a small operation possible. It can be read independently within the Alliance-Union setting.