Hmmm...The rope of life must be tread very very carefully to avoid a fall...I don't think one should show her or his vulnerable side to ANYONE in the world or tell ANYONE her or his deep secrets. If you can't keep your own secret why should you expect some else to keep your secret?
As for the weakness part...other human beings might love us but all human beings are susceptible to temptations. Also, human beings are puppets of circumstance. Even prophets have committed mistakes, our family members and friends are then just normal human beings. If a situation arises where they can take advantage of our weaknesses, they might do so, even if they love us. They might regret it later though. Why should we put anyone in that position though? Its not about love and trust, I just believe that human beings are weak and prone to making mistakes. Thus it is upto us to ensure that even a situation where our weaknesses can be taken advantage of, should not arise.