Many people obey their girl friends more than anyone else.
What if their girl friend insists you to stop gambling
Will you Stop 
What if their girl friend insists you to stop gambling
Will you Stop Lol, no, of course not. Giving up a hobby for someone else is a bad idea
so you can easily lose yourself for the sake of someone's desires. I had a girlfriend who first demanded that I quit smoking, then wanted to give my dog to a shelter because she was allergic to wool...In the end, I broke up with the girl 
LOL, not all men are like you dude. When you said that, you just showed here what kind of boyfriend you are to a girlfriend, and agree with what you also said that you broke up because you think he interfered with the routine even though you knew it was wrong. Then you just showed that you don't love your girlfriend, think that your vice is more important than the health of your GF. In other words, you're useless BF, sorry don't be offensive.
Then it doesn't depend on the reason why he stops it, don't follow it if you know it's wrong, in your case I don't see anything wrong with your GF's desire because it's for you too like smoking, you knew to yourself its bad for the health, so what is wrong with that?