The desire to control in an intimate relationship is rarely, at its origin, about power. It is almost always about anxiety. The person who monitors their partner's movements, who needs to know exactly where they are and who they are with, who becomes dysregulated when plans change unexpectedly — this person is not a bully in the way the word is usually used (though the effect can be bullying). They are a person who has learned to manage their anxiety by reducing uncertainty, and who has come to rely, too heavily, on their partner as the primary instrument of that reduction.
This does not make controlling behaviour acceptable. It makes it more interesting — and, in the consulting room, more treatable. Because control, understood psychoanalytically, is almost always a relational statement: I need you to be predictable because unpredictability is unbearable to me, and I have not yet found a way to make it bearable from the inside.