What does Proverbs 10:12 mean?

This is a key principle of biblical ethics. The general idea given here is repeated often in the Old Testament (Leviticus 19:18; Proverbs 15:1) and is cited in the New Testament (James 5:20; 1 Peter 4:8). In short, revenge-seeking never comes to a good end. It only multiplies anger and escalates a cycle of retaliation. Choosing to respond in love, instead, is far more powerful.

When people despise each another, they try to hurt one another. They argue and tear each other apart. This tragedy can even occur within a group of believers. Hatred divides and disrupts fellowship. Hatred destroys a congregation's testimony and causes unbelievers to discredit Christianity. Hatred serves the Devil. Love, on the other hand, covers faults and sins. It is important to note that love does not overlook any and every sin, no matter how grievous it might be. This verse is not referring to ignoring sin or "covering it up." But love does keep on trying to find common ground and ways to work together. It waits patiently for an offender to see the error of his way and repent. It is willing to forgive. In so far as it's possible, and reasonable, love leads us to pursue unity (John 17:21)

Jesus identified love as evidence of belonging to Him. He said, "A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. By this all people will know that you are my disciples, if you have love for one another" (John 13:34–35).