The game been crashing.

GREENAIR0103​  As a test, please try playing in a new admin Windows account.  Make it local, as in, don't link it to your Microsoft account or any email address.  You'll be able to launch the game without reinstalling it, but any user data you have left won't be available.  That's fine for the purposes of this test.

If you can get far enough to load a new save, please try playing in one of the base game worlds.

If you get another crash, let me know when it happened.  I'd also like to see the associated error from the Reliability Monitor.  Click Windows key-R and enter "perfmon /rel" without quotes, and you'll see a chart of errors and updates with a column for each day.  Today is on the right.

Look for an error that happened at exactly the time of your most recent Sims 4 crash.  If you find one, double-click it to see more details, then copy that info and paste it into a reply here.  If you don't see a new error, check back in an hour or so—the Reliability Monitor doesn't always update right away.