What do you think about me travelling and planning a future with my girlfriend? I owe money to her but think about leaving her eventually.
Why do you want to leave your girlfriend?
I have a lot of things to do. I'm not free to travel with others forever.
I'm sorry you're really busy, but you need to just break up now instead of continually taking advantage of her. She doesn't deserve to be played around by you, and if you already wanted to leave just leave now.
Just because I'm leaving my girlfriend doesn't mean we can't be together
It's best to be honest with her about how you are feeling. Dragging out a relationship that you don't want to be in is unfair to the other person.