Many people obey their girl friends more than anyone else.
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 with what you also said that you broke up because you think she interfered with the routine you had even though you knew it was wrong. Then you just showed that you don't love your girlfriend, you value your vice that 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 she 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?
Dude, I look at it differently. This is my life, I have just one and I won't have another. So I'm going to do whatever the hell I want: smoke, gamble, and get the shaggiest dogs there can be in this world. if you don't value your freedom, that's your choice, man. And I don't strive to be the best boyfriend on the planet, I strive to be a happy man