That is often what it feels like if you're really doing coalition work. Most of the time you feel threatened to the core and if you don't, you're not really doing no coalescing. In real life, a mass democratic organization needs to establish principles of unity that apply to both the goals of the group and its internal operating procedures. The issue boils down to behavior. Principled opposition needs to be respected within a mass organization as long as it is not disruptive to a degree that threatens the existence of the group.
Some disruption is inevitable, even healthy.
If a group cannot accommodate these issues of respect, then its existence is problematic, and maybe a mass exodus and formation of a new group with new principles of unity is a good outcome. The trick is to find the balance between the constant struggle that democratic and inclusive practice requires, and the ability of the group's goal to be pursued without endless splits. As Reagon graphically explained, real coalition work is hard. Individuals who repeatedly engage in disruptive behavior should be expelled from a group, as long as some sincere attempt is made to reconcile the person to the group's principles of unity regarding appropriate behavior. Nothing is more destructive in a mass organization than rumors claiming someone is a secret member of a cadre cell, or a police agent, or mentally unbalanced.