This lack of self-worth is born from lack of self love.If you don’t truly love and accept yourself, then you cannot truly accept love and acceptance from others.
They become victims to being controlled by how others think, feel about and act towards them.
In romantic relationships people often feel most comfortable around those who have a similar level of self esteem as their own.
This means subconsciously people with low self-esteem will attract others with low self-esteem.
(Which begs the question, if the only way to keep your partner from losing control is this level of hyper-vigilance, then maybe you are in the wrong relationship.) There comes a point within a relationship that you need to believe that you are with someone who cares about you and respects you enough to not hurt you.
When you trust someone, you open yourself up to the possibility that you might get hurt.