<human>: Okay, here is my situation..
In high school, I adopted two girl underclassmen because they were adorable and I am the youngest in my family. One was two years my junior, the other was three. I graduate, go to college, don't really speak to them for two years (terrible I know, and my excuse of 'I do a lot of stuff' doesn't feel like a good enough reason). 
Anyway, flash forward to now. I felt bad so I started talking to them, seeing how life is going. The youngest of my 'sisters' told me, 'You are the only boy I could ever date, but I know you aren't interested in a girl three years younger than you'. 
The older is going to my college, and well frankly I'm kind of interested in her. But I don't know whether it is the 'older brother' mentality I have, or something else. This may be because I'm a little hung up on this one other girl who is taken. Yes, well aware that I should give up, and I have. I just have awesome conversations with her.
So what should I do? I really don't want to break the heart of the youngest (I worked hard to keep her happy in high school and she is awesome), but its getting to the point where I am just sick and tired of being alone.

Could you distill the essence of the text into 1-3 sentences?
<bot>: I 'adopted' two younger girls in high school. Now in college, am interested in dating one. Wondering if I should go for it, and if it would break the heart of the other one.