There's no trust.
It is rarely possible for a relationship to work without any trust. Doubt is powerful enough to destruct even the strongest of connections because it's one partner's paranoia over the other person's words. Whether it's rooted in jealousy, infidelity, or insecurity, a relationship will not last without mutual trust. One person will end up having to live their life differently in order to make their partner feel more reassured and/or their whereabouts will always be in question.