Yes, certain exceptions should exist for deals such as this data-sharing because technology is evolving too fast to make sweeping laws and regulations. When a new data-sharing app is introduced, it must be carefully monitored to make sure nothing illegal is being done. There should always be exceptions with technology.
Whatsapp should not be banned from sharing Facebook data in Germany, because business should be allowed to make deals that they see as profitable. If a business thinks it can do better by making a deal with another company for a special arrangement, they should be allowed to do so. Anything else is interference with the free market, which is always the best model.
In Germany Whatsapp was banned from data sharing with Facebook since German authorities weren't convinced that all parties consented to the sharing. People objected to Whataspp handing over data about them to Facebook, and as long as anyone objects, the data sharing shouldn't be allowed, unless there are clear limits and clear consent.
Apps are a great way to connect with people from all over the world. Unfortunately, this incredible level of connection also means that people are sharing more private data than ever. This data should be protected, not shared, as a way to increase the safety of people who use these apps.