I'm going to break up with my partner. After all, what has he done for me?
Why do you want to hurt him?
I feel like I can do better.
It's very mean to leave someone who has done so much for you. You should be more grateful to him.
Who says I should be grateful when I am the one that he should be thanking.
Your partner has been with you and supported you in your relationship and your leaving him is rude. If you start leaving whenever you think there are greener pastures, pretty soon, no one will want to be with you at all.