What is her true intention behind dating me?

I recently met a girl at my university and I was really happy and excited to explore the world of dating. It's just that my F1 student visa has expired and I left the US (I'm from Brazil) and won't be able to return for at least 5 years, so in that sense I guess I was a little silly and knew her true intentions in advance. Anyway, I tried to have a little fun even though I knew I couldn't continue dating her even though I really wanted to because I'm crazy about her. I think I have to forget about her because I'm not going to enjoy dating someone who doesn't have real intentions. I believe she knows I'll be out of here soon and she's taking advantage of the fact that I'm already leaving to just have fun with me while she can, I understand that I can't blame her for that even though I'm a little sad about it. That's it, I just wanted to know if I was going to be able to forget her later.