Dating in the work place
If done properly, a consensual relationship agreement will make it more difficult for an employee to claim that the relationship was "unwelcome." In addition, the agreement will create a question about why the employee did not seek to stop the harassment by reporting it to management.
A rigid zero tolerance policy may result in the loss of two very good employees who fall in love with each other.
However, any policy that allows too much case-by-case discretion exposes the employer to discrimination claims.
Are any management employees involved in consensual relationships?
Are there less intrusive means to achieve the employer's goals?
Therefore, the participants in a truly "consensual" relationship cannot prove sexual harassment.