Siphoning

A name for a form of manipulation and gaslighting involving separating someone from their friends and family and isolating them.
The goal of siphoning is to have the person be dependent on the manipulator.
Siphoning may be done bluntly or subtly over time. It may happen through saying things such as:
"I am everything you need."
"Nobody else could love you like I could."
"I will look after you and care for you. Give you everything you need. You don't need anyone else."

The manipulator means to take control of someone by making them dependent and withdrawn from others.

"I was being siphoned and realised too late. I had already entrusted my darkest secrets to Charlie and he'd told me I was a monster and that only he could love me. He'd said that if I didn't do everything he said, he'd stop loving me and my heart sank. If he doesn't love me, who will? I hate siphoning."