When you respond (vs. react) you are turning down the volume dial, and turning up the effort to understand intent instead of impact. What does this mean? Whatever you say or do has meaning based on your own life experience, some of which is shared with your partner, and many years worth from before you ever met him or her. Your words and actions are filtered through your partner's years of experience and land with an impact that is often not your intent. (At times, I've seen clients intentionally lob a verbal hand-grenade knowing exactly the damage it will cause. This is different than what I'm talking about here.)
In other words, you each are wearing shaded glasses and filter everything through them. Your experiences do not make your view "right," they are simply what is familiar to you and therefore seem normal. To create a secure attachment; to be self-aware and standing on your own two feet AND inter-dependent with your partner (knowing you can count on him or her, i.e., having four feet in the relationship, not three) you need to understand each others' normal: the intention of the communication.
Three key things:
Ask questions/be curious
Work to listen and understand what your partner wants you to know
Remember, if things get heated and your heart rate is 90 or more, take a 20 minute break while you physiologically have time to calm down, and then come back for further discussion. But do state you're taking a timeout, and do come back!