Proverbs 18:19 A brother offended is harder to be won than a strong city: and their contentions are like the bars of a castle.

The natural instinct when offended is to put up walls. It is an emotional defense system. As to the offense I cannot speak. There are too many scenarios to address. The source of an offense is often the same.

We all strive to achieve objectives. It does not matter what that object is in live, it is enough that you placed importance and effort towards that goal. Things are obstacle that can be overcome or avoided but people have a will and force of their own. When we perceive a person as an obstacle towards our goal, it becomes a contest of wills. Contentions arise.

Those on the outside of these emotional offenses see right thru the contentions just as one can see thru the bars of a castle. What is not seen by the offended in these cases is that he has created a prison in which he is the only prisoner.

Matthew 18:15-16 Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.

Jesus told us not to let these things fester and to do everything you can to resolve the issue.  

Now comes the hard part. Which of the two brothers is the offender?

It is important that you choose witnesses that have no agenda in the contention. Do not ask people to take sides. Only an impartial judge can be fair to both parties and speak the truth.