Překlad - Německy-Japonsky - Mein lieber Schatz ... ich wünsche Dir alles Gute...

Romanized:
Watashi no aishiteiru taisetsu na hito e...Watashi ga inotte-iru no wa, anata ni kenkô ya arayuru ii koto ga arimasu yô ni to, anata no yume ga minna kanaimasu yô ni. Ei-en no ai o komete
Literally:
To the (very) important person I love...What I pray for is that you will have health and every (other kind of) good thing, and that your dreams will all come true. With eternal love

Note: I put the "health" before the "every good thing" because it was much more natural to say it that way in Japanese.