Help

I am leaving my 10 year relationship to find myself and to work on my mental health. My bf asks why I have to do that without him. He is a great bf but I have been having a-lot of mental health issues this year. We got together when we were in high school and I don’t really feel like I know who I am without him. I want to figure out my own stuff on my own, he told me if I come back he may not be there.I feel like its good that I am doing this before I am married. I do love him still and we have two dogs together.He doesnt fully understand my mental health issues.Am I making the right choice?