In Daystar Construction Management, Inc. v. Mitchell v. Crystal Concrete, Inc., et al., read opinion here, a 33 page decision after a non-jury trial, the Delaware Superior Court addressed various issues involving a long-term business relationship gone sour.  This aspect of the dispute involved an effort to enforce rights under a loan guarantee.  One of the more notable aspects of the opinion is that the court determined that the implied duty of good faith and fair dealing could be used as a defense to a contract claim.