I'v never been rude to her, never choose to act like an ass. Chloe already said to Imoen that "She's my girl" and my romanceactive was 2.
Just seconds after entering the 2nd level, Chloe asks Imoen something. I played along with Imoens dialog. Then seconds later I turned into the Slayer. Weird but weird things happen in Spellhold with their buggy scripts. (Not mod related)
So I confront Bodhi, then turned into the Slayer (as I'm suposed to be) turned back, slept, turned into the Slayer then had the convo about losing myself (the one you're suposed to get when you change into the Slayer for the first time) slept again. Turned into the Slayer again. This happened quite a few times. I know i'm suposed to change into the Slayer 3 or 4 times but I changed into the Slayer atleast 5 times.
The last time I changed into the Slayer I killed Chloe

After doing the Spellhold tests for the Aparition I forced talked to Chloe for a flirt but all I could choose from was the standard before romance stuff while I could flirt with her on the first Spellhold level. I loaded my save with Shadow Keeper and I saw that my romance was terminated. romanceactive 3
I am at a loss, I have no idea what caused the romance to end. Any ideas? Is death a reason for the romance to be terminated?