Whenever I'm talking to this girl, I make direct eye contact. I lock on to those fucking pupils and I don't let go. But I noticed she never looks DIRECTLY into my eyes for longer than a few seconds. She starts to look at other parts of my face, particularly my nose and other areas surrounding my eyes. Normally, this would be difficult for me to notice if she didn't do it so rapidly, but sometimes it looks like she has fucking nystagmus or something.

Anyway, I know this is the most over-analytical question of all time, but could this breaking of eye contact have anything to do with some kind of disinterest toward me?

This has been covered about 100 times but once again...
Her averting eye contact is a submissive trait, when women look at you and look down they are bowing to you, when they hold a gaze they are saying they are equal or dominant over you. Same thing if you are looking at a women, when you look down or away it is a submissive trait; just make sure you don't hold eyes for so long you start staring - if she keeps eye contact with you and it starts getting creepy look up instead of down or to the side. And no, disinterest is if she sees you and does a 180 turn and walks away not if she doesn't stare at you every second of the day (btw looking at different parts of you rapidly is also known as "checking you out" she wants you)

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To game at your best you have to be willing to do your worst.

I would do something:
1- Dont stare at her so much, maybe you are just making her feel unconfortable. By not staring, im not saying to constatly break eye contact, but im just picturing you focusing in her eyeballs and keeping a "frozen" face. Focus on your facial expression when looking at her. Express yourself a little more with your face and eye movements when listening and talking to her.
2- Tell her "i notice you keep on moving your eyes when youre talking to me. Looks like youre trying to read me!" and tell her how she looks at your nose, etc... i like to point that out to girls, they usually like the fact that im realy paying attention not only to what they say, but to their body language. Sometimes they dont even notice they do it, its unconscious, and by making them aware of it, it fascinates them.
3- if i see a girl is having trouble making eye contact, i challange her for a "eye staring contest". Something i found very powerful is, while staring, tell to yourself something like "i know youre realy into me, you cant hide it. You look at me like you want to eat me alive. We should go somewhere and do some crazy stuff", just like if you were talking outloud, but youre saying it to yourself. Believe it or not, there are some realy small details that will change in your face, like your pupils, your smile, your eyebrows... and SHE WILL CAPTURE THAT ENERGY. You might think im bullshiting... try it! I do it everytime when i toast with a girl. You will notice her facial expression changing just like if she was reading your mind. I will raise my glass and cheer, all with a deep eye contact. If she doesnt keep the eye contact while cheering, i will tell her "thats not how you cheer, you have to look into the other person's eyes!", and i will toast again!

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Im not a player... im a winner!

What I usually do is soon as possible, move and stand right next to my target. This way, it makes it really easy to kino.