Why Don't We Reach Out
#2 Past hurts.
You may have tried reaching out in the past and been hurt. Without even realizing it, you may have decided that reaching out is a dangerous thing to do. It may be something that you have to retrain yourself to do.
If this is you, consider carefully who you reach out to so that you are less likely to experience that kind of hurt again. Choose wisely and then take the risk. It's worth it.