Both are the same age, starting out at college, from the same area/hometown (kind of), both want to party and experience the greek system (if MC chooses mostly DIK choices).
I don't wholly disagree, but I think she initially went for the MC as an alternative to staying hung up on Maya. Especially when she said "Fuck me as much as you want and fill me up"
The voice of occasional sanity in my head says that this was her move to have a solid excuse to not go back to Maya. She'd already been rejected by the college, she wasn't hearing from her SO, and now if she ends up being pregnant then it's a total lock, for her to tell Maya she's met somebody and it's serious, they're over.
But DPC drama being what it is, the telegraphed scenario became clear even before the official reveal, due to the pronoun games if nothing else.
Still not sure why Derek didn't out it to MC, though considering he can't keep his fucking mouth shut about anything else.