Rivqah's role is that of matchmaker. Amongst the Riverkin, marriages are as varied as the differing religious, cultural, and political views in the Hamwech, or perhaps more so. There are many types of marriage, split along many spectrums:

Reasons for the marriage: love, politics, religion, culture/tradition, wealth/resource, status, reproduction, honor, convenience are the most common.
Style of commitment: monogamous, polygamous, trinity (three people), triad (three couples), temporary, permanent, eternal (love/religion reasons only, as it has spiritual significance), freeform, etc.
And other factors: children involved or not, who lives with whose tribe, etc.

A matchmaker's role is to facilitate people's finding those who want the same thing. She never has the power to force or arrange a marriage against someone's will. All things being equal, love is the most common reason for marriage, but not by a huge margin.

The cultural/political beliefs of a tribe will largely be reflected in the frequency of marriage styles. The most common style of commitment is a trinity, for the Arbiter is three-in-one.

Rivqah is a moderately skilled matchmaker, but like all matchmakers, her role has given her a wide network amongst the Riverkin tribes. Because of this, the Elders often consult the matchmakers on inter-tribe matters. In short, they are as much information brokers and spymasters as they are matchmakers.