Wisconsin is a no fault divorce state. The only reason for divorce is irretrievable breakdown of the marriage. Infidelity may sometimes be a factor in a custody/placement situation if there is an impact on the children. If there are no children, the fact that one person is unfaithful is not relevant or admissible in court.
Wisconsin is a "no fault" state. As a result, if the marriage is irretrievably broken, the court will seek to divide the parties' assets as equitably as possible without regard to whether or not your spouse cheated on you.