"They started to disagree on things and it stopped being fun," a source told E! News of the split. Kristen went to Germany to film and they realised that the relationship had run its course and they needed a change. It wasn't making sense for them to stay together."
They continued: "They are still friendly and run in the same circle of friends. But Kristen is happy to be back out there and meeting new people."
On Friday, Kristen was spotted holding hands with her rumoured new girlfriend, celebrity stylist Sara Dinkin, while out getting breakfast in Los Angeles. The next day, the pair was photographed going on a hike together, before heading to a nail salon.
Sara took to Instagram Stories to reveal she was taking her dogs for a walk, but declined to mention whether she was with Kristen, PEOPLE notes. However, if Kristen's uber-private past relationships are anything to go by, we probably won't hear much more than that from the two.