Questions & Answers about Toen zij zwanger was, trouwde ik met haar.
Why is the verb was at the very end of the first part?
The word toen (when) is a subordinating conjunction. This type of word introduces a dependent clause, which always pushes its conjugated verb (in this case, was) to the very end of that clause.
Could I use wanneer instead of toen here since they both mean 'when'?
Not in this sentence! In Dutch, toen is used specifically for things that happened in the past (either a single event or a specific period). Wanneer is used for questions ('When are you coming?') or for conditional events in the present or future. Because she 'was' pregnant in the past, you must use toen.
Why does the second half say trouwde ik instead of ik trouwde?
This happens because of the Dutch 'verb-second' rule. The entire first clause (Toen zij zwanger was) counts as the first chunk of information in the sentence. Because the verb must come second, the main verb (trouwde) comes right after the comma, pushing the subject (ik) after it.
Why is there a met in met haar? The English translation doesn't say 'married with her'.
In English, you 'marry someone', but in Dutch, the verb is always trouwen met (literally: to marry with). You cannot leave met out in Dutch when mentioning the person you are marrying.