How do you not have trust issues?

If you have been hurt, it is difficult. I have found, that people for the most part are not trying to hurt others, but rather are focused on their own desires and wants. They may value their desires over your needs and find ways of justifying hurtful behavior.
Of course, forgiveness is the key to restoring your own ability to trust, but it is not easy. Forgiveness is not about giving the person who betrayed your trust a free pass, it's about not allowing that same person to remain in control of your heart or feelings by choosing to hold on to that hurt.
Having said that, it is in fact, really hard to get there. It took me nearly 30 years to forgive my father and most of that time, I didn't even realize that it was effecting my decisions and my choices. I finally found the grace to forgive him, even though we never restored a relationship. By forgiving him, I simply minimized his role in my day to day thoughts and decisions.
I think recognizing that we are all flawed and we all tend to from time to time be self absorbed allows us to extend more grace to those around us. Again, Grace and forgiveness should never be a permission slip to allow someone to continue to hurt you, but rather a pass to allow them to slip from the center of your thoughts to the outer borders.
Sorry if this isn't relevant to what you are asking.