To enter into a marriage is a solemn vow. Breaking that vow is either a sin against your God or your partner. Either way, you are breaking a promise. Integrity is one of the few things in this world that is exclusive to humans, and we betray it all too often. It is better to divorce and carry on in such ways. Accept that you could not keep your promise and make a declaration that reflects that.
I do not believe wife-sharing has a positive influence on family life. I believe it can set the foundation for youth to have the wrong ideas about appropriate relationships or what is common in normal society. Wife-sharing is not common so exposing it to children could cause problems for them in adulthood. Thus, it doesn't postively influence family life.
While every family is different and needs to make decisions based on it's own individual needs, the practice of wife-sharing is sure to cause major difficulties in the average family. While wife-sharing may be intriguing to some, issues such as jealousy and extra-marital pregnancies are sure to arise and create a rift in not only the relationship but also possibly with any children in the household.
I don't believe that an open marriage, such as sharing a wife among multiple men, would be a positive thing for family structure. There would potentially be mistrust in this type of open marriage, with people not really being fully devoted to one another. Similarly with polygamy when there is husband-sharing, it also creates an issue with there being too many of one gender. Some sects have had issues with there being too many males when the men have multiple wives.
No, I don't think that wife sharing has a positive influence on family life. While I'm okay to a point with any alternative family relationship, I still think that the best way to raise a child is with just 2 or 1 parents. And those parents must have clearly definable relationships to the child.