It sounds like you should have this discussion with your girlfriend.

You disagree over whether you should smoke pot, so you do so in a way that may be drawing unnecessary attention to yourself and by extension could be putting both of you in danger if by some chance the police DID arrive, smell pot (that's all the 'probable cause' they need to enter your home), and charge you or both of you with possession. Worst case scenario.

On the other hand, if the neighbors already dislike you enough that you suspect they are capable of pulling a slimeball maneuver like that, you have bigger problems.

Time to offer to help your neighbors shovel their driveway next time it snows... a little ass kissing goes a LOOOOOONG way.

And really, anything you are doing in a home should be to the approval of everyone who has to live there. You guys should chat.