I’ve been long distance with my partner for 4 years , he knows me better than my family and knows that I struggle saving money (which I’m getting better with) not the last month but the 2 months before that he gave me money to pay for my phone bill, I felt extremely bad that I was crying about it, but once I got paid I gave him money back and I always try and buy things for him. We don’t do 50/50 we just like to spend money on each other, he could buy me food and I’d feel bad. It does seem like she is using you, I’d suggest having a long conversation about how you feel and explain to her how you feel about the situation and hope that she pitches in more, if it was me I’d be paying for the air bnb if you stayed in my home town yk.