Why did she drop this so fast?

a really good friend of mine told me she was in love with me. She told me all these nice things and asked if i was willing to give her a chance. She is so nice and polite and i really did enjoy going out with her but i'm not used to being romantic with a woman so when she asked to kiss me i got a little jumpy. After a week she told me it was alrite and that i didn't have to try so hard and she was alrite just being friends. I tried to tell her that i'm trying and she said that the fact that i'm trying so hard means that this probably isn't for me. I really want to try but she just dropped it. Why did she give it such a short run?