Upvote:2
Assuming your country citizenship is not on the list of Annex II countries, you will need to apply for a short-term multi-entry visa.
You will need to provide the proper documentation to support both trips and request that the visa is issued for a duration that covers both periods of your stay. In the worst case scenario (assuming your documents are in order), the German consulate will issue a single-entry visa for your first trip and afterwards you will have plenty of time to apply for another visa for your second trip.
Also note that once you get married, it will become much easier to apply for EU visas as you will become a non-EU family member.