Ah, with a boyfriend already here it's simpler in any case
Is he German or already here for some time?
Something like a language learning tandem might be a good chance to get to know locals, I know a lot of foreign students who did that to meet new people and learn/improve the language in a fun way
Plus there is a huge English-speaking expat community in Berlin, getting into that is even easier (Craigslist etc.) probably.
Though in the more "neighbourly" (that is not in the touristic centres where there are more Air B'n'Bers than regular tenants) areas you can mix up with all sorts of people quite easily as you start meeting the same people in your immediate surrounding (Kiez) again and again
(folks are married with their Kiez
, the more peculiar my trans-city move, but I'm indeed done and fed up now and looking forward to the new place
)