How to not be insecure in a relationship?

Don't let the example of your parents ruin your relationships. You have trust issues. But has your current relationship had any trouble and has the other person given you any reason to doubt their motives or intentions? Going to a therapist could really help, they can help you get rid of the pent up bad feelings and make you see clearer. Your significant other is not trying to hurt you or else they wouldn't be in a relationship with you to begin with.