There is actually some good research on abuse, (which includes controlling behaviour) and the root of it is that the abuser, whether we are talking a romantic relationship or an employer or a parent or a child, believes themselves to be entitled to servitude from the victim.
A good analogy is this. A great many people have pet dogs. They love their dog and care for it. They take it to the vet to keep it healthy. They provide it with food, shelter, exercise and companionship.
They might think "I'm a good dog owner, I would never hit my dog!" "I can't stand those awful dog owners who leave their dogs outsode overnight." They consider the dog a member of their family. They choose the food that the dog prefers, they buy a bed that it finds comfortable. They DO, genuinely, love their dog.
But at the same time, it's a dog. When they have visitors who don't like dogs, they shut it in another room so that it doesn't bother them. When they go on holiday, they might put it into kennels or with a family member. When it has to stay overnight at the vets, it stays in a small cage. When they go out for a restaurant meal, the dog gets its own ordinary kibble or tinned food. They expect it to obey commands. They keep it on a lead in public places. There are certain foods and rooms in the house which are off-limits. They do all of these things and they are still a good dog owner. These decisions are totally appropriate because a dog is not a human.
The abusive/controlling person thinks much the same way about their romantic partner. They love them, they appreciate them, they take good care of them - so they think. (I'll switch to he for abuser, she for victim now because they is too confusing)
But if the victim starts to get out of line, it's totally appropriate to pull her back into line somehow. That might be subtle like letting her know that she has upset him, or hurt his feelings. Subtle manipulation to get her to feel she has to "make it up" to him. If she is demanding too much then she has to be brought back down to her proper place. She is not really an equal. She is beneath him, her role is to adore and serve him and she can only expect certain things from him. When she starts to expect too much, he needs to let her know.
The abuser might not be consciously aware that he is placing her in this role. Indeed, in male violence/control towards women it is generally a kind of unconscious view about how all men and all women relate, with women being on a lesser rung - they often have a hierarchical view of how men relate to each other, too, with more physically domineering, or otherwise powerful men higher on the ladder, but women are right at the bottom with lesser men. It just seems so obvious and innate to them that they probably wouldn't articulate it - but you'll notice little signs like they never look to women for their opinion/don't take their opinion seriously on serious matters. Jokes that play down women's intelligence. In his mind it's "just the way things are" and movements like feminism are unfair because this is women wanting to climb the power ladder without the proper merit. They will sometimes respect certain women who do play to the rules of what they see as the male power game, but the majority are down there at the bottom, and women (especially "their" woman) refusing to play to the rules of that game and accept their position are being uppity and entitled.
In fact, it is the abuser who is entitled. It is very difficult to change this because in order to change this they have to overhaul their entire view of how society works and how people interact and it is not a comfortable thing to give up their relatively high position on that ladder. Abusers who do perpetrator programmes to learn how to be not-abusive commonly have the question "But if I'm not allowed to hit my wife, how do I get her to do what I want?" They do not fundamentally grasp that they do not have that right - that their wife has the right to choose what she wants to do. That a partnership is about communication but each person equally in control.
So in terms of whether they know what they are doing and choose it - yes and no. They are choosing it in the way that you would choose to correct an unwanted behaviour from your dog (or your child, though we recognise a child is learning). They are not consciously choosing what they see as their rightful position in the relationship. But for me once I understood this I could not be in the relationship any more, because I understood that I was not an equal in his eyes and would never be. He was seeing something totally different to what I was seeing and we would never be on the same page.