I do feel like a lot of the posts on here come from people with very atypical teenagers.
I've worked with teenagers for decades (and was one, and have one). While you do meet a few who are solely interested in school work and wholesome hobbies at 14, and utterly happy to comply with any Draconian regime their very strict parents choose to impose on them, such kids are in a minority.
It has ever been the nature of teenagers to push boundaries, and to start forming strong and often unsuitable romantic/sexual attachments, whether reciprocated or not - and most children with very strict parents simply find ways of going behind their backs to do what they want to do, making it much, much riskier.
OP, the strength of your situation is that your daughter currently appears entirely open with you. That's brilliant, and a credit to your parenting. I am sure you will find a way to deal with this situation together - the fact that your dd has identified the boy has controlling ideation is also very good.
Good luck. And parenting a normal teen IS a minefield, to anyone intelligent - getting the balance right between protection and allowing appropriate freedom to grow, in a rapidly changing world, is HARD.