A User has Paths, which have Blocks
If 2 tables are 1:1, then probably they should be a single table.  If 1:many, then 2 tables and the 'many' table has the id of the other table.  many:many requires a 3rd table.

It sounds like you have 1:many, so you don't need the user_paths table.

More on optimal schema for many:many.