This is a proposed revision - The problem is with the basic last question, not sure how to phrase it to not get a lot of "Well, only the players can tell you that" type of responses:
I have been DM'ing for a few years, and due to my upbringing I prefer to run games that don't really allow for what I consider to be evil acts in game. For me, that means using basic common sense and not doing things a law abiding citizen wouldn't do in real life, so no murder, torture, etc.
While I haven't had to enforce this rule very often, there have been times when I've gotten into arguments over what actually constitutes 'evil', and the argument is generally that D&D is a game, and that I am trying to enforce my own value system on the game/players.
Here is the scenario that caused the problem. I created a town in a kingdowm that had increasingly oppressive and binding laws, until the populace got fed up and deposed the ruler. One of the laws that wasn't repealed, however, was the law against selling alcohol. My intention was for the party to solve this problem through using charisma checks in discussion with townspeople to vote to drop the law, thus enabling them to open a tavern as a business for passive money in the game.
The players essentially ignored this and turned into murder hobos, and ended up burning down a different village to get their alcohol. I asked them several times if they were sure, and then started a different encounter planned for later in the game early. I was trying to get them to correct their actions to reflect the house rule on evil, but that backfired and they ended up quitting on the game completely, and I have not heard anything from the group since then.
This was very disheartening for me, and I'm not really sure if I had done something wrong in how I approach the game. Where did this go so badly they felt their only recourse was to quit?
Any/all suggestions welcome on phrasing the last bit.