Hello: My 1st wife was kind of like you. We would somehow get into an argument and I never knew how to handle it or keep from being sucked into a fight with her. It was like this for the whole time we dated and then married for 25 YEARS! No kids, thank god!
Neither of us knew anything about good relationship skills [google it] like: Fair Fighting, Avoiding criticism, being best friends and a lot of other powerful relationship skills that could have saved our marriage plus, she was very afraid of intimacy after being screwed over by previous guys. I went into therapy (I was the sick one - NOT HER! LOL!) and began to learn about good relationship skills but when I tried to show her these skills, she laughed it all off as utter non-sense so I ended up divorcing her! WHAT A WASTE!
I don't give advise but this is what I did and my current marriage is TERRIFIC! I entered therapy and attended a lot of 12 step support groups like Codependent's Anonymous and studied up on relationship skills so both my now wife and I USE them to keep us in good stead and ever improving as both best friends and hottest lovers!
good luck fixing your issues,
jim