Why she wont forgive me completely?

Girl I had friendship for 8 months,and recently we became really close she asked me out hugged wanted to kiss me.and made plans.and was even ready to lose her virginity withe me,but I said that she should wait a bit till she is really sure.

But a got angry about something and we had an argue,next day i apologized,but then i screwed up again and really hurt her with my words.I really regret what i had done and couldnt sleep all night Next day i made a huge apollogy,and said that i will change(I really am trying and i want to be good for her.) She said she can forgive only half. She forgave me with her mind but not with heart yet. As she said.

She however is a bit bipolar she sometimes didnt care about me but always came back apologizing afyer a week or more. She sometimes plays mind games to.

But what it usually means when girl says she needs time to think if we can be otgether,and that she cant forgive me right now completely?