When is the game crashing, when loading saves? Do they consistently crash, or if you restart the game can they load if you retry?
There are a couple of known issues which can cause a crash during gameplay (selecting the wedding cake, or sometimes an issue with a particular skill used by an opponent in combat in an area after Kemm's garden). A patch has been finalised and I think the Switch version has started the submission process.
Try clearing the system cache, if you have not already done so: in the Home menu open System Settings, then select System, Formatting Options, Clear Cache and then the current user.
Note that this will also reset the system language and brightness setting.