Hi J Connor,
Under normal circumstances of the property being located within the UK, a deed of trust may be created to split any rental income between yourself and your civil partner at the same time transferring legal title to your Civil Partner, however as it is situated in Germany, I would advise you to contact the German tax authorities for clarity on your personal situation.
Also, please see PIM4702 which outlines some guidance which may help to gain a better understanding on some of the options, as this may need to be declared as foreign income on your Self-Assessment Tax Return:
Property Income Manual PIM4702 - Rent from property outside the UK: Income Tax (IT).
Thank you.