I'd actually say the lead up to Archie's death when she lost yet another baby when he shoved her into the bar or something was when they were starting to get silly with the storylining for her. It was all a bit daft as Danielle's death should have been enough motive.
But the character started to go down the wrong path around the time of poking holes into Joel's (Danielle's father) condoms and then it outright ruined her with the baby swap storyline.
So the actress made a good call in leaving to rest the character and they had the perfect opportunity to fix her when she returned after paying for her crime, but they decided to get sillier with her instead.
