Better to be occasionally cheated than perpetually suspicious. (B. C. Forbes)
The best way to find out if you can trust somebody is to trust them. (Ernest Hemingway)
Have you ever been burned; I mean really burned? Have you given your trust to the wrong person? Perhaps it was a love who pursued you relentlessly only to dump you when they caught you. Maybe it was a marriage partner who abused you, berated you or cheated on you. Did a parent abandoned you or a friend betrayed you. Perhaps it was a co-worker who stabbed you in the back resulting in job loss and financial issues.
We all have our tales of woe. People who "done us wrong". It stinks.... and there is really no cure for our hearts when bad things happen to us but to grieve and move on. Part of moving on means to forgive. If we hold on to the grievances for too long we become bitter and ugly people.
When we forgive it doesn't mean that person is "off the hook". The truth is that people are going to have to live with the consequences of their actions. The fact that they were untrustworthy says more about their character than yours. In addition, most of them stand to lose the relationship because your ability to trust in them has been compromised.
Often when we have been burned we resolve that the problem was that we trusted too deeply. To trust is human and an act of love on our parts. To react to bad eggs by becoming suspicious of all others, only cuts off opportunities in our lives to have solid relationships with positive people. Not everyone is untrustworthy, in fact I still like to believe that more people have integrity than don't. To become an "untrusting" person will only hurt you in the long run.
This isn't to say that we sidestep the "getting to know you" process and jump in too quickly with intimacy and deep secrets. Proceed always in relationships with wisdom and caution. Never give too much too soon, but keep your innocent and trustworthy nature.
So if you have been burned in a big way and have resolved never to trust again, take a step back and consider how many people HAVE been trustworthy in your life. Don't cut yourself off from the masses and from love because of a few big duds.... Take a chance and trust .... it's good for the soul!