In an ideal world, parents would never argue in front of their kids. Losing your cool and yelling probably isn't really a lesson us parents want to pass down to our children, right? However, in the real world people get mad and sometimes they react without thinking about their audience. That's why there are certain things my partner and I do every time we fight to make sure our kid is OK. I know losing it in front of my son is an inevitability from time to time, so it's important that I find a way to explain what happened and how my partner and I are going to fix the problem.
My son doesn't necessarily understand that even though his father and I argue, we still love each other. So, honestly, it wouldn't surprise me if watching his parents loudly disagree is nothing short of scary. I also think it's important for my partner and I to show our son that we're human and we make mistakes. I want him to know that we're both flawed, as romantic partners and as individual humans, but that we work hard every day to behave in a way that will make our son proud.
In my opinion, it doesn't really matter whether or not you fight in front of your kids. Instead, what matters is that, as parents, you show your kids that you can repair your connection with your partner, nourish your relationship, and conduct yourselves in a healthy and productive way, even when you're upset. My partner and I try to show our son that behavior in the following ways: