Jealous Husbands

Several couples went on a picnic and had to cross a river in a small boat. No husband would leave his wife in the company of another man unless he himself was present. Given that everyone could row, how could this party cross the river without jealousy arising, if

there were three couples and the boat held two people;
there were four couples and the boat held two people, and there was an island in the middle of the river;
there were five couples and the boat held three people?

(From Henry Dudeney's Amusements in Mathematics.)