Jealousy is harmful to relationships. That isnt an opinion its a fact.

Jealousy destroys relationships for neurotypical people all the time. A person with severe mental illness is already dealing with enough to just keep a roof over their head and food on their belly. They also have to deal with stigma. They also have to deal with their mental health symptoms. They are impaired.

I have seen repeatedly that a person who lives with severe mental health issues gets in an abusive relationship and because they are afraid of loss of stability if they aren't in a relationship, they stay with the abuser.

This increases the amount of stress that the person is under, worsens their symptoms, and increases the likelihood that they will have a severe crisis reaction. This could lead to suicide, psychosis, substance abuse/dependence, violent behavior, running away, manipulation and abuse by others, and many other harmful but common outcomes.

It's a simple equation: Reduce symptoms by reducing anxiety. Increase symptoms by increasing anxiety.