There's this girl I've known for a couple of years now. I really really like her. But she has a boyfriend who is in USA, and she hasn't even seen him for 3 years now. What should I do? Should I go for it and ask her out? Your help is much appreciated.
Thank you.

Try reading this guide first: https://www.askmehelpdesk.com/dating/guidlines-what-do-do-if-person-like-already-relationship-463250.html

If you still have questions, ask away!

It doesn't matter if he is the house next door or across the globe or if she has seen him five minutes ago or three years. She is in a relationship and unavailable for you to ask out.

I don't think you would like it if she were your girlfriend and went out with someone else. You would call it cheating, wouldn't you?

Instead of pursuing this girl, find one who isn't already taken.

Speaking as the girl with the boyfriend of 3 years and a boy (we'll call him Joe) who approached me when I was dating said boyfriend (Bob)... the situation was different because we all lived in the same city. I had issues with my boyfriend Bob (he cheated) but felt stuck with him for various reasons. Chances are, if she hasn't even seen him in 3 years then it isn't much of a relationship anyway. I vote that you be a good friend to her (like this boy was to me) and chances are you'll have your moment to shine.

This boy found the right moment to (very respectfully) say that "I was a great girl and that he wishes I were available, my current boyfriend was very lucky" and then he completely laid off the topic. I told him then that I couldn't talk to him anymore (I was quite shocked and felt guilty because I liked him too). But shortly after that (weighing my options) I broke up with that old boyfriend and started slow with Joe. We've been dating for 6 months and I have never been more happy. :)

Ask yourself... why is she with this guy? There might be a good reason. And would she be offended if you said something to her? Always, ALWAYS play the gentleman... if Joe had made a physical move on me I would have written him off as a creep and never talked to him again. Just be prepared to lose your friendship with this girl if you're willing to make a leap. If you really like her, look out for her happiness first; you'll never go wrong.

Thank you very much lilian. Really appreciate it. She also told me that she has some issues with her present boyfriend. But the thing I don't understand is, she talks to me whenever she can and we chat online like 24/7.

Let me tell you - it's so much easier to stick with what you're comfortable with. If she's been with him for 3 years, there's a chance she doesn't know how to let go... that's a long time to be with one person. Just be patient and give her some time. It sounds like you're doing everything right. Just be a friend to her for now and be really careful not to cross any lines. Always respect her feelings first. It was a really hard thing for me to do, I'm sure it's not easy for her either. When the time is right to let her know how you feel, you'll know!

Speaking as the girl with the boyfriend of 3 years and a boy (we'll call him Joe).

Man this "Joe" seems like a great guy congrats for you and just do what lillian says she sounds like she has helped a lot of people and people always say that women give the best advice:)