When you split up with someone, it really should be a clean break. Don’t “taper off.” Don’t hang around the same places. And of course – this usually goes without saying – don’t pee on her door.

That last item is one of the many cardinal rules of breakups allegedly ignored by a 20-year-old St. George man, according to the Staten Island Advance.

Police say Isaiah John repeatedly telephoned his ex earlier this month, even though she had a protection order forbidding that. Then he went to her home, yelled outside her apartment door and urinated – perhaps a primitive way of marking her as his territory.

He is also charged with approaching the woman outside his building two weeks later and raising his hand as if he were going to strike her, according to prosecutors.

The Advance quotes court papers, in which he’s alleged to have said, “I have money on your head. … I’m going to get my girlfriend to beat you up.”

This also would be poor break-up etiquette.

He is charged with criminal contempt, menacing and harassment, but commended for staying hydrated.