Because they do not know or care about the right way. It is about self-serving, power, and control.
Because he wants the sex and the control over you. It is all about keeping you under control. And for a woman, sex is emotional, therefore, attachment, therefore control.
Per the last sentence of your first paragraph and the first sentence of your second paragraph, your ready to get out.
He was already realizing it before you got to this point. Hence the cuddling and sex to gain control.
Don’t be scared, be strong! Don’t worry about what he is doing, concentrate on what you are doing. You can do this.
Here for you when you need to talk. Hugs.
Chickadee