The husband perhaps is afraid of being thought of as a perv for bringing the subject up, The wife will usually wonder WHY he wants to do this, perhaps having a feeling of inferiority, not being enough woman to satisfy the hub in the usual ways..Sex outside of marriage is still somewhat looked down upon in our society even if both partners are willing to try it.. Another reason may be simply finding a third who is compatible and makes both the hub and wife feel comfortable taking this big of a step. There is much more to this than jumping in the sack with some BBC picked up at the corner tavern.=p