Everyone is human and we're fallible and make mistakes. We also all have different personalities so we may handle situations different. How do you handle when your upset with someone? Get your feelings hurt? Disagree with someone? Don't get your way? Offended? Let's be honest sometimes in these type of scenario's we're the problem, because we're easily offended, looking for something to be mad about, insecure, jealous, or other reasons. But, sometimes it's legitimate and how we handle it makes all the difference in the world.
Our goal in situations like this should be resolution. Many times the offender or the person you may be hurt or angry toward might not even know you're upset or they did anything wrong. Sometimes it's a matter of perspective and we're too sensitive and need to get over it and sometimes it's legit and we need to address it.
However, what happens many times is we don't address it or deal with it. We keep it inside and we might act different toward the person, being cold or rude or unfriendly to them subconsciously or even more dangerous we let it build up inside of us until we blow up on that person or someone else. That is not healthy and I also believe it can lead to sin. In the Lord's prayer it tells us to "forgive us our trespasses as we forgive those who trespass against us."
I also think the Bible backs ups the fact that we shouldn't allow things to fester on the inside and that when we have problems or struggles or issues that we need to deal with them while they are small before they become bigger or out of control and take on a life of their own. So many conflicts and problems could be avoided if people would just be honest and talk to each other when things arise, instead of ignoring them or letting them build up and before you know it, there's tension, a fight, argument , hard feelings, etc...and for what? Many times for silly, stupid, or unknown reasons.
I would encourage everyone to first make sure you're not the problem and your own worst enemy, making sure the reason you are mad, upset, hurt, offended, or angry isn't because you've got issues going on. Secondly, if it is a legitimate case of it, then deal with it at the lowest level, is it worth talking to them or letting it go? Thirdly, if you do decided you need to confront or talk to them, do it in love, sincerely, and with your goal being resolving or finding resolution.
Whatever you do, don't let those negative feelings build up in you because they will cause you to sin and not be a very good person and they will cause you to have strained relationships if you're going around blowing up on everyone because you let it fester.
So watch yourselves. “If your brother or sister sins against you, rebuke them; and if they repent, forgive them.
“In your anger do not sin”: Do not let the sun go down while you are still angry