I'm sorry you struggle with trusting others and didn't grow up with trusting. I didn't lose my trust until later in life and yes it hurts. Think we all wish we could trust, but still have some realistic suspicions, otherwise we would surely get taken advantage of. Maybe the best way is so assume we might get hurt, but its better than not trusting and being closed off completely. Think its reasonable to be mildly mistrusting and street wise in todays society. Get to know them very well and watch how they behave with others.