I'm sorry to hear things worked out the way they did, but I'm glad to hear you'd dealing with it well.
I agree with BoringGuy, he sounds more like a serial monogamist than polyamorous. Let him be her problem now. Let her pay his bills and tuition.
It's times like these that I'm somewhat relieved polyamory hasn't made it in to the mainstream. Underhanded perhaps, and sets progress back... but now you can play the "he cheated on me card" as far as the legal system goes. Sure, it's not literally cheating; he told you what was going on and you agreed to it. But he violated the terms of your agreement, which is what cheating ultimately amounts to.
You were supporting him financially on the assumption that he would eventually use your support to get a higher paying job and contribute more to the household finances. You basically made an investment in him.
Leaf should be scared. He's giving up financial security. He's giving up an easy way to test new girlfriends. Now he'll have to sneak around behind her back the way everyone else does.
I almost feel sorry for this girl. Almost, but not actually. She brought it on herself, cowgirl all the way. She's in for a harsh wake-up when he does the same thing to her in a few years. But she'll have to excuse me for misplacing my sympathy a few miles below the Earth's crust.
I've never understood people who take people away from their partners. How do they not see that it's only a matter of time before they're on the other end of the cycle??
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker