YOU ASSUME THE WORST
If you are so insecure that you automatically assume the worst of your partner, it shows a profound lack of trust in the relationship. Without that trust, the relationship will have a hard time moving forward. If they were just stuck in traffic but you come after them based on your fears rather than actual events, you will drive a wedge between yourself and your partner. Give them the benefit of the doubt until they prove themselves untrustworthy by their own actions.