Buttercup was getting ready for bed, as she was thinking of all the people she had gone out with. She dated Mitch for the heck of it, she dated Elmer because she felt sorry for him, and then there was Spade, from Citiesville. She hated that place with a passion, but she had met Spade online. As luck would have it, he turned out to be Ace's cousin, which would explain the green skin. She hadn't picked up on this at the time, but she felt stupid for not knowing it. "Stupid, stupid, stupid!" She had said to herself. She couldn't believe she hadn't noticed the similarities between the two. They acted the same, walked the same, and even talked, the same. How she hadn't noticed this, she had no idea. She just knew one thing for sure, it was late, and tomorrow, she was going to start her first day of school. She needed her beauty sleep. So she went to the bathroom, washed her face, and went to bed. As she slept, she dreamt of Ace, missing him.
This is a bit short for a chapter, but it can work fine as an epilogue.
Personally I prefer Hibbles (wtf I have a fave pairing in PPG, wtf!?) Despite that, I think that AcexButtercup is a pretty good pairing.
To me, this does sound like an AU ficlet. Which I'm not a fan of, but hey it's your story do whatever you want with it.
But I must say, that Buttercup is OOC in this. I don't think she's the one to feel pity or spend time with someone just because of it. I can't imagine Buttercup dating load of guys, going out as on a one/two time date - possible, but not actually a mushy boyfriend-girlfriend thing. The beauty sleep - also I don't think it's a very Buttercup phrase.
AU - Alternative Universe. It doesn't necessarily mean a fiction that is taking place in an absolutely different universe, this term is not limited to that. It basically means any type of fiction that is not consistent with the original.
OOC - Out Of Character. [IC -In Character]
No problem. I hope you're not offended, I honestly said what I liked and what I didn't like. This was a critique. You can tell me if you don't want me to comment on the upcoming chapters of your fic and I won't.