I'm in no position to say what adcoms will like or not. I can only speak for myself ... I don't really care if this was a girlfriend, a wife or some relationship that you created in your mind during late nights. As a reader, who this girl is/was/will be doesn't matter. The only thing that matters is your perception of her and what she has taught you. I think you do a good job of conveying honest feelings. Does it matter if she was a friend, but now you're dating? I don't think so. If anything, that will adjust the focus from what you have learned to why you have learned it (bc you grew close to her). As a reader, I want want to know what the author has to say. No one's going to be judging you on the context of the story. This shows that you can write, that you're human and from some sort of experience, you've learned. Details don't matter. Even if you aren't dating her, the way that you portray yourself and your emotions during that exact moment is all that matters ... to me.