I'm thinking of manipulating him so I can leave him.
Why is it important to you to leave him?
I'm thinking of leaving him because he deserves it.
It is not good to manipulate people. If you want to break up you should just tell the truth.
It seems like my way would be easier.
Manipulating him is not the right way to get what you want. You'll be seen as dishonest. Face the issue head on and with honesty.