I am currently playing in a testsave without Mods/CC (trying to reproduce another bug; pulled the localthumbcache before creating a new vanilla save). My Sim wanted to ask another Sim to be her girlfriend. They were on their homelot. Want still did not complete. Hope my info helps!
I've been having the same problem the last few weeks on PC. My Sim keeps getting a task to ask someone to be their girlfriend. I have asked the Sim to be the girlfriend and it does not complete the task. It will remain there for a day or two then dismiss itself. I have even asked the Sim to be my girlfriend, had them broke up, and then had the same issue repeat. If anyone has any solutions that would be great
