The one place Aryaman is unmistakably central is a marriage. The Rigveda's long wedding hymn, the one built around the mythical marriage of Surya, calls on him directly, and the invocation stayed in use. Sanskrit marriage liturgy retains him in the formulas that release the bride from her father's household and settle her in her husband's, and a girl of marriageable age is described in Vedic language as one for whom Aryaman is to be sought. The verb is the same one used of asking for a share.
That fits his character exactly. A marriage in this material is not primarily a private emotional event; it is a rearrangement of obligations between two families, conducted according to custom, and it works only because both sides accept what is customary. That is Aryaman's subject.
The rest of his later history is a quiet decline of the sort common among the Adityas. He acquires no temple cult of his own, no iconographic type, no body of myth, and he survives chiefly in three places: the recited hymns, the marriage rite, and the lists of twelve, where he stands near the head in both of the standard Puranic orders. The astronomical tradition also assigns him a lunar mansion, Uttara Phalguni, which is one of the reasons his name remained in circulation among astrologers long after it dropped out of ordinary devotion.