In an effort to add more females last year, I acquired three "girl" ducklings. One turned out to be a male, and the three formed their own sub-flock. Lane would march his two girls into a separate coop at night and hang out with them in the daytime.
By winter, all nine ducks -- three drakes, two of which were ducklings together, and six hens -- were happily housing together, and all three boys "share" the girls. There is very, very little trouble among the boys, who will often wait their turn in line (it's weird, actually) to breed with a particular hen.
I can't imagine you won't fall in love with runners.