Changed plans without letting me know

[ThePerkyCoralPoet]

So I agreed to meet up with my friend, I said we could meet up as just the both of us. That was the plan. She helped me with securing a job by sending me interview prep etc and so did her partner. I got
rhe job and that was because of them both partly helping me. I then said we’d get dinner altogether on another night(which I could get). We had agreed that it would be just her and I getting dinner today.
This morning she texted me saying her partner would be joining us. Which is fine I don’t mind but I didn’t account for paying for this meal so now I don’t really know what to do. I know it’s not really socially acceptable to turn around and ask that either. Like are they expecting me to pay?

@Drom

Presumably enough notice that OP could make plans with other friends if having the partner there wasn't what she wanted?

Just be honest and say 'I had only budgeted to pay for you this time, I know you both helped but you know what cash flow is like when you swap jobs with tax codes changing to emergency tax codes etc, so hope you're OK to pay for hubby'

I would literally say do you want to treat you at this meal as you are both coming or save it for next time?

I'd be put out if this happened but only because going out with a couple changes the vibe.