She has a nose that is kinda big, but not too big, above average I guess, she has average eyes, cute little freckles, straight hair, and funny looking teeth but they're straight. she's short, and has an OK body... and sometimes when I look at her I think she's average at best... Yet most of the time when I see her I think she's the cutest girl I have ever seen... Whyyyy? And yes we like each other but its a bit awk between us.
Now there are a few different answers to this question; and each one will be dependent upon the beliefs of the answerer.
I believe in a very scientific explanation for most things, and this situation does have a scientific answer.
Every person, even most animals in fact, produce pheromones, which is an invisible and scentless hormone that attracts members of the opposite gender. You, for whatever reason, are quite possibly attracted to this individuals pheromones.
Now remember that this is not very solid science, and pheromone attraction does not by any means excuse or force any actions on your part. That is the benefit of being an "advanced species," we are able and expected to behave as the culture dictates as exceptable. So be nice, and make your decisions based off of what you think is best