Your significant other says something that they shouldn't have. You have to ask yourself, "Should I engage in this battle and spend my time and energy trying to straighten them out, defending myself and arguing with this person while trying to prove that I'm right?" Even if I win this battle , what am I to gain, what will this fight accomplish?
For instance, that person who cuts you off in traffic and you get upset, you immediately go into payback mode and in turn cut them off. Somehow you allow this event to ruin your whole day. But ask yourself, "what was the benefit of today's action?" You didn't even know the person and minutes later they're not even in your life! So what's the point? Sometimes we get so distracted fighting battles that doesn't really matter.
We need to choose our battles wisely. Should we be in constant defense mode all the time? We spend inordinate amounts of time upset with others, or various disputes with family. Time is valuable, is it worth expending all of your energy and wasting part of your life? If we keep making the mistake of engaging in every battle that comes along and constantly defending ourselves proving ourselves to be absolutely right, We will not have the energy to fight the battles that matter.
You see, there will always be opposition. Don't let those bad episodes drain your energy. You will need it for the really important stuff like living a good life. Resist the mistake of consistently proving your point, straightening someone out, or trying to change another person's opinion. Listen, we all have real battles that are really important. If you are with someone who don't want to be with you, move on. Even if you lose what appeared to be good friendship, it probably wasn't worth it anyway. Leave the petty battles alone. Save your effort for the important, meaningful and fulfilling things that come your way.