AITA for going to New York alone after my girlfriend said it was too expensive?

I’m 20, currently studying, and my family has a small business where I worked during the summer to save some money.
I’ve been with my girlfriend for five years. We’re long distance, I live in Italy and she lives in Poland. Luckily flights are quite cheap, so we see each other pretty often, usually almost once a month.
The last year has been really difficult for me. Last year, my stepfather died on the exact same day as my dad’s birthday. My parents are divorced, so imagine having to celebrate your dad’s birthday while also finding out that the person you grew up with while living with your mum had died very young after a serious illness.
He left behind my two younger siblings. We share the same mother, and since I moved out, my mum has been left alone with them. They’re still quite young.
All of this affected me a lot. My studies suffered, I’m struggling with exams, and I feel a lot of responsibility towards my mum and siblings.
Then, just last month in August, shortly before my birthday, my maternal grandmother passed away too.
At some point I just thought, this has been a terrible year and I want to do something nice for myself. So I decided to go to New York.
I saved the money myself from my summer job and booked everything. Flights, accommodation, everything.
The problem is that my girlfriend currently works, so she can’t just come with me. When I suggested New York, I said I wanted to go because I’d had such a difficult year and wanted something positive to look forward to.
She said she wasn’t sure because it was quite expensive and she would have to see what she could do with work. I completely understand that. I don’t expect her to spend money she doesn’t have or risk problems at work just because I want to travel.
So I decided to go alone.
I want to make something clear: this is not really a relationship problem. I’m not angry with her, and I don’t think she did anything wrong by saying she couldn’t come. I simply want to know if I am the selfish one for deciding to go anyway.
If she wanted to travel alone or with friends, I genuinely think I’d be happy for her. I’d miss her, but I wouldn’t expect her to stay home because we’re in a relationship.
I’ve already booked everything, so the trip is happening. I’m just worried that from her perspective I might be doing something selfish, especially since I initially imagined us going together.