Sometimes I find that Origin and/or Sims 4 won't open at all for me, until I restart the computer. I'm trying to track a pattern but haven't found one yet. I wondered if it's that issue of having to...
If you are using Windows as your OS , the game's process might be starting in the background.
What i would sugest is instead of restarting your PC when that happens you might wanna try going into task manager and see if the Sims 4 process is running and close it.(it should be called something along the lines "TS4.exe".
Underneath are a few links to help you out with task manager on Windows 7 through 10. On Windows 7 you have the specific "Processes" tab and on 8 and 10 you will find the processes in the "Details" tab: