"Love bombing" is the the manipulative seduction technique that involves showering someone with so much affection and then deliberately making them feel like sh*t by taking it away.
Psychiatrist Dr. Dale Archer wrote about this phenomenon in Psychology Today, explaining:
Love bombing is an attempt to influence another person with over-the-top displays of attention and affection. We’re not just talking about romantic gestures, like flowers and trips. Love bombing invariably includes lots of romantic conversation, long talks about “our future,” and long periods of staring into each other’s eyes.