This might be one of those curly questions that are difficult to generalise about but "How do we know when to part company with individuals or groups that we have been associating and interacting with?"
Christians are called out of the world, out of darkness, out of bondage, and out of sin, and into God's Kingdom, into the light of the Gospel, into liberty in the body of Christ, and into righteousness, so what does that mean with regard to the direction we go, the intention we have, and the position we take?
One thing is sure from Scripture, Christians are to consider one another and fellowship regularly, assembling or gathering to encourage and exhort one another.
Heb 10:23-25
(23) Let us hold fast the profession of our faith without wavering; (for he is faithful that promised;)
(24) And let us consider one another to provoke unto love and to good works:
(25) Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as you see the day approaching.
I remember well the departure of a highly regarded teaching elder from a congregation of around 300 gatherers being announced in a service as due to his not being happy with the direction the denomination was going in. A word of knowledge had been given to this elder at just the right time to help him decide that it was time to part company, so unhappiness is one thing but divine guidance should be sought and accepted as well, I believe.
Anyone...?