MySQL - Should I create a different database for users
If the data is related, it should be in the same database unless there is a very compelling reason not to.  By separating the data you have:

Made it impossible to maintain referential integrity
Increased the number of cross-database calls
Increased the amount of maintenance
Increased the likelihood you will build another database for analysis/backend reporting with complex reconciliation rules

If you are looking to improve fault tolerance or increase performance, there are generally better ways to manage that.