One of my Sims is attracted to her father

I hate that! I don't play with Mods or CC(except occasionally the one below very briefly in the way mentioned, then I clear out everything right after), but I do have issues with this type of thing happening too.

I've gotten where if it happens I tell one of them that I control to talk to the other and 'ask to be just friends'. That will take the romance bar to zero. Some other things you can do that sometimes helps is 'turn off attraction' on certain sims (you can do that by just clicking on them and looking through the pie menus), and sometimes I even go in and remove attractions for them if they are something like my butler or other household NPC that is on the lot a bunch.

There is a pretty simple mod, UI Cheats, that I have popped into my game briefly to actually remove the romance bar entirely. I've even before moved a 'romance bar' relative into the library to sever their relationships (and romance bar), then put them back into the family and popped back in that same mod just to recreate their family relationships... then I remove it afterward. It really upsets me a lot when something like that happens, so I feel your pain. I've had mom/daughter, aunt/uncle, etc. sims in my households where these things happen lately (maybe since Lovestruck?).

I don't play edgy character traits or lifestyles or behaviors that would make me think something like this could pop up. So upsetting!!!!!