yea its really very horrible thing our friend didn't talk with us for no reason. You just wait definitely he/she will recognize our true love and they will be back to you. Because our love and friendship is really true....
I think you give the other person time and then try contacting them in a month or so. I think that is the beauty of e-mail to try and "break the ice" and attempt contact that way. Just an "I've been thinking about you" type of email.
