it is coz she loves you machan.
for a girl who is serious about n affair, the affair matters a lot. she'll so ny thing to hold on to that connection. specially if that is her first love also. some event do not eat n drink when there is a problem in the affair. they value the connection that much.
now please do not start saying there are bitches. yes there are. I agree. but not all a so. and to girl to become a bitch there is a boy who played the part of director in most cases otherwise it runs through the family of the girl. most cases boys do not understand the requirements of a girl. that is the first step of a breakup.
any way it seems she loves you so much machan. even though she forgave you the hurt is still there with her. she will silently cry about what happened even in the future. try to make her mind up. coz if she thinks you did it because of something is lacking with her that mindset will prevail for long time. try to ease her sorrow coz it is you who is responsible for her situation.
good luck bro.
do not loose a girl who really loves you. they are really hard to come by...