Cancer in the Navamsa places the Moon's own cardinal-water sensitivity over the marriage house, and the union it describes is read as emotionally rich first and practically organized second — the relationship's center of gravity sits in feeling, home, and family rather than in logistics or ambition.
A spouse indicated here tends to be nurturing and protective, someone whose care is expressed through domestic attentiveness — building a home, tending to family, remembering emotional needs before they're voiced. The marriage itself is traditionally read as carrying real depth, with the couple's bond to each other's families often as significant as the bond between the partners themselves.
The Moon's own changeability is the classical caution here: this placement can bring mood swings into the relationship's emotional weather, and a tendency for the union to lean too heavily on one partner's need for reassurance. Its brighter expression is a genuinely safe, caring home; its harder edge is difficulty maintaining independence within that closeness.