It is illegal to sue someone for "alienation of affection" if they steal your spouse.

The Law

In older times across the U.S., a jilted spouse could sue the person their partner ran off with for destroying their marriage. Hawaii officially outlawed these 'heart-balm' lawsuits to prevent bitter, vindictive litigation from clogging up modern courts. So if someone runs off with your partner, you are legally barred from suing the homewrecker for your broken heart.