i can't turn a close friend into lover

That is sad. But I understand. There are people we just like to consider as friends because we don't want to ruin that relationship. Being lovers are much harder and in the end, we break thing apart. That's why friends are much better than being lovers.

Hi, What I can say is that you are a lucky guy. Since you don't have any chemistry on this close friend, then it is better to tell her frankly one day. Find the right time to tell her about your feeling,at least, you don't give her a hope and let her know how you feel towards her. You guys still can be a close friend,but no fate to be a boyfriend/girlfriend. Don't hurt her feeling so deeply,that is why you need to solve this problem as soon as possible.

Yeah, it will indeed make her sad. You don't have to force yourself to be involve with someone romantically when what you have for that person is mere platonic. Friendship can still exist and would be much appreciated this way when there's no romantic inkling whatsoever. I admire you for maintaining that friendship and not abusing what she have for you.

I know that this is a difficult situation, what to choose friendship or love. I guess it really all depends how you feel, it seems like you don't feel the same way she does. I would personally say, if you feel the same way as her I would take my chances and give it a try you never know what could happen. My husband and I were in the same situation, but we decided we wanted to give it a try and we have been married for 10 years and together for a total of 15 years, so sometimes you need to the risk. But that's a decision you are going to have to make. She has expressed her feelings and you have returned them as well, so she will definitely be disappointed and/or upset with you when you tell her you don't want nothing else but friendship. So don't be surprise if she avoids you for a couple of days.