I'm going to refuse to let my boyfriend do what he tells me he wants to do.
I'm intrigued. What did he say that he wants to do?
He wants to be a teacher when he finishes his education in a year.
It feels very controlling of you to try and tell your boyfriend of what to do with his career. He may have a passion of being a teacher and I feel like it will make a strain in your relationship if you would not let him do what he's passionate about. You wouldn't want him to ban you from doing what you want, would you?
I'm only trying to help him. Teachers have too little time to spend with me and I need him to spend more time with me.
Well, I agree, teachers can be too busy and may not have a lot of time for their personal life, but I think you just got to learn how to live  with it and try to think about those times that he spends with you as more precious than before. He will be helping students if he becomes a teacher and he will help them to learn about life and I think you should support his choice.