My therapist says behind resentment there is hope. A hope that things can be different and better. If we didn't want things to improve, we would care less, and not be resentful. What is behind the resentment? Is it telling you what you do want in life or in your relationship? Is what you truly want shared with your partner? If you both want the same thing, then that is a good starting point. Next is building the skills to make that happen.

When people fight for 4 hours over a "little misunderstanding", what are they getting out of that? If they know it is a misunderstanding, why don't they say so and straighten things out, instead of fighting for 4 hours? I don't have the answers. Maybe both people are getting something out of the fight (stimulation? relieving of other stressors in their lives?) if they choose that instead of a clarification to relieve the misunderstanding. Or, maybe sometimes it is that we get stuck in these non-productive patterns and do reach a point where we have had enough and won't do it anymore and are exhausted. Reaching that point of exhaustion can be a good thing, as then we are willing to consider alternatives. If you find a good couples therapist, he/she might be able to help you through. With entrenched patterns (if that is what is happening here), it can sometimes take an "outsider" to pull us free.

Good luck.