I tend to be on the other side of things. I get so many messages from people (text, email, fb) that I often feel overwhelmed. I feel so much pressured to respond-- even when I don't want to or don't have time to. I would say that if you are always the one initiating the messages-- and your friend is not initiating any contact-- then it may be a sign that she is distancing herself from the friendship, for whatever reason (too many other commitments, other friends who are closer, too many hours at work, etc). When someone is feeling overwhelmed and pressured, the LAST thing they want is even more messages or a guilt trip for not responding. That is probably the fastest way to push someone away. I know not hearing back from a friend sucks, but it sounds like she is busy and has other commitments or relationships that she is prioritizing right now. Do you have other friends you can reach out to instead?