For some people it's not as simple as liking/not liking.
I think I speak for most INTP's when I say that it usually takes time for us to get a solid sense of direction in any relationship, before we are willing to commit fully to it.
Agreed, I'm a very social guy who has no problems to talk to complete strangers, and make them feel comfortable around me. However establishing an emotional connection.
I like it if a person can call me out on my bullshit and tells me how I'm undermining my own happiness (point nr. 1). Also challenging me to achieve something better then I currently have is a good motivation (2). Don't tell me to do something, but offer it as a better alternative without discrediting the other options (3).
A great example was when I was in my last year of high school, my grades were so poor the school either offered me a choice of making exams of an easier education type or do the entire year again. I pondered on this for a while but couldn't find what the best option would be. Both of them are in itself acceptable options, but neither of them really appealed to me.
Then later when I was talking with a friend of my mother, we were discussing the situation. In short he said:
1. "Let me get this straight, you don't have to choose either of the offered choices. You can still make the exams with poor entry grades as long as you finish a lot of open projects on a really short term?"
- Making me realize there was a better option.
2. "You're more then competent enough to do this, you're the smartest young man I've ever met, just get yourself together and spend some time on your school work."
- Challenged me. I felt such a shiver through my body when he said this, cause I at that time realized I always knew I could seriously do this and that other people had just talked me out of it.
3. "If you finish high school this year, on the level you're currently at, you can go to university next year and you'll be free of all this. You can get on with your life. Make a fresh start, and do what you want."
- Making me realize this really was the better option for me without discrediting the other options.
4. "What do YOU really want."
- Me answering: "You make total sense, I'm going for it."
In other words. I'd tell this girl again that you really love her, and tell her you'll be there for her if she wants to, but that playing these emotional games is getting to her as much as they are getting to you, and that she's not going to be happy about it. This other guy is her ex, the relationship must have ended for some reason.
Unfortunately nobody can tell you the exact words to say to her. We don't know the situation half as well as you do. You also work in a much different way from me. I'd pre-script questions I'd ask her and have a full story ready before I'd go and talk to her. That is not necessary however if you don't like the idea of speaking from the mind instead of from the hearth.
Wait a bit for the other people to either disagree or agree with my post. Rationally speaking it's a bit unreliable to go from one guy's experience, even if he happens to score the same as the subject on a psychology test.