Explain to your partner the importance of taking this course for your own personal development, and that by doing so you can only become a better person all round, including in your relationship to him.
It is important to address the issues that are really surrounding his concern and fear, these feelings may go beyond you wanting to learn an grow by taking this course. Perhaps he has feelings already that there is something wrong in your relationship that needs attention or addressing.
In your communication with him, try using this phrasing, that will help him to go a little deeper into his feelings and beliefs. You can begin with the phrase “If you could know why you believe that by me taking this course and evolving more in myself that I may not want to be with you any longer it is because”…..and then let him answer. Or another phrase would be, “If you could know what it is you are really concerned about it is”…….let him answer. Or say, “If you could know why you feel that by me growing I would no longer want to be with you it is because”……let him answer. This will allow him to see what is under the surface what is bothering him.
We all have some fears, beliefs and patterns that will come up from time to time in our relationships, and the biggest challenge is to remain open, communicate, and share these things with one another, in a relaxed, loving and calm setting.
We should never stop the person we love from doing what they need to for themselves, because we want to control the situation around us in order to make ourselves feel better, so as not to feel our fears, old patterns or negative feelings about ourselves that we need protect or do not want to feel inside. We should take the steps to heal those feelings and beliefs within us.