Everyone makes mistakes; even some of your behaviours could irritate the other person. Therefore, the best course of action is to start by focusing on what they do well.
Take a day to solely think about his or her advantages. If you can, try to let go of the bad things for a week by doing this.
Is there something they've been doing that you don't like? Tell that individual, then! Communicate! If not you, then who else will tell him or her?
They might not even be aware that what they are doing is wrong. Explain your concerns to your spouse over a meal.
You two need to stay away from everything for a while. Take a trip, even if it's just for a stroll or a lunch date? It greatly reduces stress and also helps to calm the mind. When it's just the two of you, that time is crucial.
Games of blame are unpleasant and unfair. No one is perfect, so you both have committed mistakes. So why do it dirty? While occasionally complaining is acceptable, why not embrace the rings you agreed to and make a promise to one another to do better?
If everything else fails, consult a therapist jointly. It's possible that there are minor details that you two haven't been able to discuss.
Only an impartial third party can make a note of them. Here, therapy works best, and it is worthwhile! We all want peace in the end, after all.