I could probably shoehorn my experiences to fit these stages, but I'd rather not.
I'm short on time but I'll try to be as detailed as I can in the few minutes I have to spare.
Let me start with the most significant dualization experiences I've had. First, there was the ESE from high school. It was so strange - we hung out in totally different cliques, me with the chess club (mainly ILIs, who beat me silly, one other LII guy) and her with her cheerleader friends
but I felt like it was her and I against the world, we didn't speak much, but when we did, it seemed like we didn't have to. We understood each other in a way that felt like we had known each other for years - a lifetime even. She'd generally avoid speaking to me when her friends were around - they didn't like me much - but if I got her alone we'd sort of go into this bubble, not allowing anyone else into it.
I don't think ESEs are like this. They always seem to be so proud of who they're dating. ILEs have a much looser definition of relationships and are much more likely to do something like what you describe. ILEs lack the confidence in their relationship that ESEs just ooze, and you don't pressure them to demonstrate it--thus this completes the dualization. Take VixenFoxDog for example. She's always singing her dual's praises, right? Your girl is different though.
I eventually fell in love with her but didn't realise it. Weird, huh? In my mind we were too different, and I was expecting to end up with another introvert. Everyone else on the other hand noticed. They kept on making comments on how "playful" we were in each other's company (which strangely seemed to be PolR based, she'd pretend to be very Se and I'd pretend to be very Ni, which annoyed her, which I found really amusing.) Only after consistent comments from random people I saw that it was only me who hadn't realized the feelings I had for her yet.
The polr is a blind spot. I think that if someone jokes about it, you probably wont "get" it and if you have to think about it, then you aren't being dualized. That's not my point though--this love formed very organically almost without any sort of turning point where you knew "ok now we are in love". Again, there's no pressure, no expectations, just a "flow". That would put you in irrational territory. LIIs need to know where their relationships stand, and ESEs are the ones that give them constant status reports. If you had any expectations like that, I'm starting to think that girl would have run off, scared of being stuck in a committment. (that's what I'm starting to notice with my relationships anyway, ILEs get spooked when you try to get a committment out of them)
Gilly mentioned somewhere that Fe dual-seeking sometimes manifests itself by mimicking the behaviors of the Fe ego - that I can relate to. I often shocked myself picking up some of her mannerisms.
ILEs look very closely for emotional cues from you. They rely on your rich vocabulary of facial expressions because it puts them at ease. LIIs don't really mirror their ESE duals as much. They remain fairly unexpressive, but somehow the ESE has the confidence that they are still hitting all the right notes with them. ILEs, on the other hand, need constant feedback that they are doing everything right. It's like your quiet way of controlling the mood and you're doing it with Si. Having that uber-expressive face is more helpful than you might be aware of. When someone is talking to you, they see immediately if they're being understood, or if you get the joke, or if they just offended you, or whatever. ESEs don't really need that, although everyone appreciates it to some degree. I remember I had this one ESE teacher that said my constant feedback actually made her nervous. So maybe LIIs need constant verbal assurance while ILEs need constant nonverbal assurance.
Whenever I'm around my dual, I'm relaxed enough to where I can start speaking my mind and making jokes that I know he/she wont be judgemental of. I've said it many times: Bad jokes are funny too.
Secondly, I have a cousin who is ESE, Fe subtype. This will probably be most useful to the other LIIs. I don't see her too often, but now that I'm all clued up on socionics, I take every meeting with her as another opportunity to understand duality a little more. She has similar dreams and ambitions to me, which is awesome, I often consider everyone else's ideals to be incredibly silly. We walked around in a shopping center once (she dragged me there) and she decided she was going to talk about some relationship issues she was having. To cut a long story short, she would spit out the details of random events and then just stop and stare at me. I assumed she wanted me to pat here on the back and say, there there, you'll be okay. I mean, it's what she usually does when I behave in an emo way so I assumed she wanted the same thing, only to realize after reading some posts on this forum that it was probably her Ti-seeking trying to get me to make sense of her situation for her.
Another thing she does: if we're at a party, I generally move away from the crowd to a spot which is more quiet, and I put my earphones on and listen to my metal (I hate the rap rubbish they usually seem to play around here) but she will come find me and drag me back into everyone else's company, where the Fe is at. She can't stand the feeling that I'm being left out.
She seems to have this freaky understanding of how my mind works. For example, she'd invite me to some sort of shared recreational activity. My focus will always be on the "point" of the activity. For example, knitting. I'd say, but winter is so far away. She won't try to rationalize why we need to knit anyway, she gets that i'm not seeing that it is more about the social interaction than the activity itself, and she will point this out.
she seems more like an ESE, but it doesn't seem like duality either. It seems like she's focused on being social while you just want to have fun (competitions can be fun too) and she's not helping you, she's correcting you. Compare this to the other girl that would avoid talking to you when she was around her friends, your cousin doesn't seem as content to leave you on the sidelines while she socializes. You sound like you want to sit down and tune everything out because you don't like the music, not because you feel awkward or anything like that. You could say that's putting preference for Si over Fe.
That's all for now, I'll come and be analytical later.