Some scriptures are easier said than they are done. When things get heated between us we must apply the scripture and not allow offenses to make there way to our hearts. Bitterness is a heart condition, it takes place when offences are allowed to curdle like spoiled milk in our hearts. If you have ever tasted spoiled milk it is a taste that is very hard to get out of your mouth just as bitterness is hard to get out of the heart.
The fact is in marriage we will most likely Hurt, offend and upset each other. But we must quickly forgive before the offence is allowed to leave its stain and bad smell in our hearts.
Do you remember why you got married, do you remember the love you had when you said "I DO"? What has changed since then? Could it be bitterness and or resentment has taken up residence in one of your hearts? If it is your spouse that is resentful, no matter how hard it is go to the top of this post and read the scripture and apply it just as you apply the prescriptions you get from the doctor. If you don't apply the medicine it won't bring about healing.