Gibbs based one of his rules off of his third wife.
After dealing with the fallout from his relationship with Diane, Gibbs married a woman named Rebecca Chase. Their marriage didn't last long, but the two would occasionally cross paths. As part of her alcoholic recovery program, Rebecca made an effort to mend her relationship with Gibbs and to let him know she was marrying her divorce attorney.
During a crime investigation, Gibbs was shocked to learn his two ex-wives, Rebecca and Diane, knew each other. Coincidence? He thought not!