She's behaving very similarly to Lucy as a younger teenager.
But the new Abi makes sense, it's the good one that didn't, but maybe that was Jay's influence, he kept her on track, just like he's trying to do for Ben.
Abi has had a rough ride-her parents constanly rowing, cheating, leaving and even trying to kill each other, her sister almost dies, she fails every exam she seems to take, loses her boyfriend and kills her dog. Being good wasn't really working and she flipped out.
Meanwhile her sister got to do what she liked, drank til she got sick, slept with whoever she wanted, yelled at and smacked her friend but still kept them, got given jobs with ease and ends up with fiance and baby.
not a surprise she dunked Lauren with the apples really lol