I'm no expert, but it's usually a described as a feature of abusive relationships, or cult recruitment techniques, and involves things like:

"Flattery, verbal seduction, affectionate but usually non-sexual touching, and lots of attention."

"Deliberate show of affection or friendship by an individual or a group of people toward another individual. Critics have asserted that this action may be motivated in part by the desire to recruit, convert or otherwise influence."

I'n not saying what therapists do IS love bombing, but I do see parallels. Therapy is usually framed as something medical, which i find insane, and so i look for other analogies/contexts to make sense of it, and one is social control and manipulation.