It may range from occasional meetings with a man away from her husband through to a regular lover who visits the couple at their home.
Often a couple will progress into more serious cuckolding when they find they enjoy the lifestyle.
Cuckolds are often allowed to masturbate while they watch their wives have sex, some wives will not even allow their husbands this relief!
Generally the husband derives his pleasure from his wife's enjoyment.
The term "bull" denotes his superior sexual prowess.