The Suspicious Six

Three married couples are waiting on the west bank of a river. A small boat can carry either one or two people, and everyone can row it. The couples are unusually jealous. At no time may a wife be on either bank with another husband unless her own husband is also there. The same restriction applies inside the boat during a crossing. People may make as many return trips as necessary, provided every bank, boatload, and arrival remains valid. Starting with all six people on the west bank, what is the fewest number of one-way crossings needed to bring everyone safely to the east bank?