It's not uber uber bad? Well I guess it is? Lmao. I mean it's a bad end.
I can give you the jist under a spoiler. You can look at it or not it's entirely fine either way but it gives you an option to know it if you end up not doing it at any rate!
So you sort of pick the wrong choices going through like telling RD not to let go of the kid and saying EH to the festival etc. You also sort of go through the story bare minimum. Think I ignored the poster also.
SO anyway the WORLD LOVE DOMINATION PLAN actually succeeds as RD can't talk her out of it and RC ends up under its spell too.
The bad end is essentially the world succumbing to it, RD being upset cause RC is also under it. Cupid leaves earth and doesn't help her and essentially it's implied shes going to spend all her free time, years and years learning how to make an antidote to save her partner no matter what it takes.
It ends before it lets you know if she ever succeeds or fails so essentially you are left in limbo with her going to devote her time into saving her and no answer =p
So yeah! You don't have to look but its there if you need it! Not the worst worst worst of bad endings I've ever had but it's not an ideal one either.