Hate to tell you this, pumpkin, but no man is going to leave you because you're too nice and too courteous. If anything he's threatening to bail because he's probably somewhat of a d-bag and you're making him feel guilty. Perhaps he's done some less than savory things and wishes you'd find out and tone it down or something.
Fact: people want to be with nice people. Nobody wants to be with a snarling bulldog. So if he's threatening to leave because you have home-training, well, he's lying.
There's something else there and you'd be served well to recognize that. Surely, he does need to just get over though if a man doesn't want you to pamper him (how exactly are you doing this? Does this just include ironing his drawz or cooking? I'm curious.) then perhaps you could tone that down. But once again, who wants to leave a situation because things are TOO good? Somebody who doesn't feel they deserve that because of whatever reason.
Keep it in mind.
Some guys get bored without excitement, spontaneity, or even a little dash of drama. If he's saying you're too nice, maybe what he means is, "I'm bored with you." And if someone's unhappy, telling them "to get over it" doesn't really fix anything.
I can't help but say something about the comment. Relationship is not a one way street, it takes two to tango so how about he tells her that he's bored and propose to do something exciting with her to spice up the relationship. He has other reasons than her just being too nice