Breakdown of De nieuwe laars, die pijnlijk was, wordt steeds wijder.
zijn
to be
nieuw
new
worden
to become
die
who / that (relative pronoun)
Questions & Answers about De nieuwe laars, die pijnlijk was, wordt steeds wijder.
Why are there commas around die pijnlijk was, and how does it affect the meaning?
This is a non-restrictive (or extra-information) relative clause. The commas show you are talking about a specific new boot and just adding the extra detail that it was painful. If you removed the commas, it would become a restrictive clause, implying you have multiple new boots and are specifying which one you mean (the painful one).
Why do we use die here to mean 'which'?
The relative pronoun must match the gender of the noun it refers back to. Since laars is a de-word (de laars), we use die. If it were a het-word, we would use dat.
How does steeds wijder mean 'wider and wider'?
In Dutch, combining steeds (continually) with a comparative adjective like wijder (wider) translates to 'increasingly' or 'more and more'. It is the standard way to express an ongoing, gradual change.
Why does the verb wordt come immediately after the relative clause?
The main sentence is simply De nieuwe laars wordt steeds wijder. The subject is De nieuwe laars, which takes up the first position. The relative clause just interrupts the subject. Once the subject is finished, the verb-second (V2) rule applies, so the conjugated verb wordt must come next.