Background - it's after work, I've had a long day and we have made plans to go for a run and play golf when we get home.

She's been out all afternoon with her mother and sister and I'm waiting for the train home. We're texting back and forth and we work out it will be slightly quicker for me to come to them and for us to get a lift home with her mother than to wait for the train so I uber out to them (about 2km but 25 mins in Melbourne CBD rush hour)

Before I ordered the uber I explicitly texted "do you promise that we'll go home the minute I get there" to which she replied yes.

So when I get to them she says that we're going for a drink in the south suburbs (we're currently in the north so it'll take a while to get there) and I get annoyed and ask if she's taking the piss in front of her mother and sister.

She explains that she wasn't really reading my messages as they were shopping and that she thought I would have been open to the idea of staying out.

I feel that she's refusing to see that the only reason I went out to them was because of the promise of going home straight away as we had plans that we were looking forward to and she's refusing to accept blame for this and is instead focusing on my negative reaction.

Things got really heated and spiralled with neither one of us backing down.

Am I the asshole for getting mad at my girlfriend in front of her mother and sister because she switched up the evenings plans in this way?