It is if you looked at a picture of her before even knowing her and said, "Oh, I wanna fuck her so bad right now" and masturbated to her. As long as you don't do that you'll be fine. For real though, you've seen her personality, how kind she is, how considerate she is and how much she cares about others. It's natural to fall in love with a girl who is that kind.(Even if you are a masochist). Just take your relationship slow, don't rush it. Accept her shortcomings and give her time to accept yours. Also stay as friends with the girl who rejected you and reassure her. I've known stories of people who are afraid of being confessed to because they fear that their rejection of them can lead to broken relationships. Just make your girlfriend happy and stuff. It's not too fast right now.