I proposed a girl,she said I dint expect this from you

I have proposed a girl with whom im I am friends from such a long time.
But she said I did not expect this from you....
What should I say in reply to her?
she has been a good friend to me....and we both r not in commited relation or love till now.....we have been as friends.
But I love her from the bottom of my heart........i want her to be my life partner

You have said you proposed to a girl who you are friends with, right? Please just make one thing clear here, are you friends with this girl or are you in a commited relationship with her because if you are just friends then of course she would not expect that from you.
It will make it much clearer if you say if you're JUST FRIENDS or A COUPLE.

ADDED BIT: OK thank you for clearing that up. Firstly you need to tell her how you feel about her because if you just go proposing to her she will probably be slightly confused and maybe scared off. Explain to her how you feel and if she reciprocates your feelings then take it slowly, but rushing in straight away it may make you seem desperate and maybe carzy. I hope I helped you a little.

I know we see surprise proposals on tv and in movies all the time, but in real life I think the couple should really discuss it first. They should make sure they're on the same page, have the same values, have compatible life goals, know each others financial history and debts. Marriage is a major decision, not an romantic whim.

Maybe you could say to her that you realize you surprised her with this, and that you didn't mean to catch her off guard. Explain how you feel for her and ask her if you two can talk about where your relationship is headed. This will be the perfect time to see if she wants the same things you want. She may also want some time to think things over.

Try to be patient. There will probably be many conversations about it over a period of time... unless she's not interested in taking things to the next step.