I'm not sure if my friend will be reading this. I just want to give my expertise, since I self-study psychology, social engineering and some 'black ops' stuff (underground psychology, not many people, even psychologist might not know this) This emotion of loving "difficult ppl" is not hard to understand.

You stated that nice people are simply not for you. Oh man, I'm strike out of the list. Lol, its not my initial motive anyway, so who cares. Haha. And you like people who is "difficult" to love. There's actually a reason for this. This fact is scientifically proven, tested, but is remained unknown to the public. Its no big secret, but people who knew this either is a PUA (pickup artist), psychologist or an "information junkie" (like me) since there's not much reason why one would know this.

I'm not saying everyone who applies this is a PUA or a psychologist. Most people do this not on purpose or is unconscious that they are doing it or even that they do not mean to invoke this feeling.

Haha... I will keep you all still in the mist for a while. I notice this stuff being repeatedly used everywhere. In reality, in TV drama. I doubt the scriptwriter even know about this but wrote story that has this element cause they observe this through normal human interaction, social interaction and by reverse engineering social behavior.

I won't continue with so much technical term (that I may be unsure of their real meaning), so the secret is simply this. Female prefer male who give them emotional roller-coaster. You might be saying... huh? That's all? Yes... its suppose to be just so simple, but to prove that I do not simply come out with a so-called "love philosophy" that is made up by me. I wrote so much above to show that its true and is credible. Not discovered by me. Its by the phD people and years of research...

Okay following this is MY own interpretation of why this fact is like this. I may be wrong but since I am an very high INFP ( I will state what each letter mean later), I am more reserved but have an extra "sensory" to others feeling (aka social engineering). Female are more emotionally orientated, so its more likely to hook into an emotional roller-coaster relationship. If its minor, its quite fun and add spice to ones love life but most emotional roller-coaster relationship is pretty unhealthy.

When you are in an emotionally addictive relationship, you constantly feel like you are on a roller-coaster with soaring highs and lousy lows, moving you between glorious feelings of ecstasy,
followed by horrible feelings of agony. You know that you shouldn’t be there as it is against your better judgment and against everything you believe, yet you feel paralyzed. You can’t leave!! It is a very difficult decision to make and even more difficult to carry out.

Sound familiar?

Those are just a few characteristic of emotional roller-coaster. I figure that her emotional roller-coaster is not really that bad yet. Its either she can try to improve her own relationship or get out of it as soon as possible. That's the only 2 ways she can do if she want to improve or make it better. If she do not do anything, she might even get worst, or even if its turns out better eventually, she will be very prone and weak to another of such emotional injury. So 1 word of advice, take action. Oopse, that's 2 words = /

So now she knows why.

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Ha-ha, as promised, this is what INFP means

Introverted (I) 96%
Intuitive (N) 91%
Feeling (F) 85%
Perceiving (P) 77%

Different sources may have different breakdown of what each word mean, but in a nutshell, I am introverted, but have an extroverted social observation. I can interpret and analysis what happen in social interaction but am not very good at it yet.

However, when I was in relationship myself, I can never figure out what's going on. So generally, Im better at viewing from a witness stand point then when I am in the situation itself.