Feeling like a stranger

My girlfriend and I have been together over a year, and when things are good they’re really good, but lately little things have been making me feel like she doesn’t care or refuses to listen.

Like the other day she wanted me to take her to get food before work (I was driving), and she got upset because I told her that I’d be late for my work.

I told her I didn’t appreciate her getting upset at something out of my hands, especially when I’m already driving her to work, and I wanted her to just be happy that I do everything I can for her within my ability.

she kept telling me she loved me and that she’s trying in the relationship, but I knew that and I tried explaining that’s not what I was upset about. Then she shuts down, saying she doesn’t want to talk, she acts like I’m a stranger and saying she “doesn’t know me” which of course upsets me further.

At the end of the day we always apologize and admit how stupid are fights are, and that we care for each other, but we keep having them.

I’m doing my best to control my emotions but little things always turn big because she doesn’t listen to my actual concerns and she tries acting like my feeling aren’t valid.

Im starting therapy soon, but in the mean time does anyone have any emotion controlling/grounding techniques to calm down and focus on reality instead of being stuck in my head?