Re: Sims 4 will not launch through my account

@ZER0T0  Just to clarify, are your (not your fiancée's) Steam and EA accounts linked to each other?  You can check by signing into any ea site, e.g. ea.com, with your Steam credentials and checking which EA account loads.

This isn't a typical issue, and I don't know of any files that would cause this considering you used your own account to install Sims 4.  But since Origin was previously installed, it's worth removing all its cache files, which may or may not have been removed along with the program itself when you installed the EA App.  This guide was written for Dragon Age, but it's the same either way; just substitute in Sims 4 where you see DA:

https://answers.ea.com/t5/Other-Dragon-Age-Games/can-t-launch-dragon-age-2/m-p/12199080#M24626

If that doesn't help, uninstall Sims 4 and the EA App, create a new admin Windows account on the laptop, install the App and Sims 4 using that account, and try to play.  This will remove the influence of any data associated with the current Windows account, so it's a useful test even if you don't want to switch to a new account permanently.