He's blue balls deep in a long distance relationship. Met a few times

He seems very serious about this one. About to move in together, 'yolo' style. He has no personal financial knowledge whatsoever. We were brought up pretty comfortable so there were no incentive for us to learn personal finance.

I feel like manipulating some stuff so he can get his heart absolutely shattered when he eventually breaks up. He calls his girlfriend a lot in the living room and I just know it's going to go to the shits within 3 months.

Let nature do the work or add in a bit of spice to 'help' his future self?

And I don't mean stealing his girlfriend.

He won't listen to anyone. My parents do give pretty sound advice from time to time (mostly financials). But he will never listen. I want him to wake up and I see this as the perfect opportunity to do so.