I've been around 6 months in germany so far, however I don't speak german but certainly most of the people living here do speak english.

OK, here's the thing. Most Germans have some level of familiarity with English, that's true. Many can even speak it, particularly those who are well educated or work in the service industry. But most Germans are not fluent in the language.

If you're not fluent in a language, conversing in that language is difficult. It takes a great deal of concentration. You have to listen carefully, mentally translating the words and then processing what they mean, keeping an eye out for verbal and non-verbal cues and contexts to fill in the gaps where your language skills fail. When you respond, you can't just respond, you have to think about your response, translate it in your head, and then try to pronounce it correctly.

All of this is hard, stressful, and taxing. Its uncomfortable. And, unless that person is looking for an opportunity to try and improve their German, they may not be willing to go through all of that in their off time. Asking them -- expecting them -- to converse with you in a language they're not comfortable with is asking a lot, and is particularly unfair if you're not willing to take a stab at German.

As others have pointed out, as well, there are also simply some cultural differences at play here. People here don't, generally speaking, socialize with random strangers. They participate in clubs -- vereins -- for that very reason. There are tons of clubs fir a variety of different activities. Soccer clubs, biking clubs, hiking clubs, shooting clubs, archery clubs, even drinking clubs.