I have a sim that just started the Romantic Explorer aspiration, and has a goal to Have a Romantic Partner. Thing is, she's married to her soulmate, but that goal is not completing. This may .be related to a previous bug where being Promised would block completing having a romantic partner in the Soulmate aspiration. I have not checked to see if that bug is still active. This save has had mods disabled from the start.
Version 1.113.277.1030 DX11
Edit By Crinrict: Adjusted Title fit migrated bug report: [ARCHIVED] [LS] Romantic Explorer: Have Romantic Partner doesn't tick off | EA Forums - 11719123
Archived thread had around 1 me toos
