How many relationships (sexual, friendships, etc.) do you know that are an obvious mismatch and go on for way too long, hurting one or both parties? It happens constantly.

If you think this guy is driving you to a breakdown or is starting down that path by overestimating your ego strength, then I still say what I did before, he's bad news. Competency and harm are not mutually exclusive in any practitioner.

Do you think he will listen to you and change or accommodate to your needs or wishes?