What should you do now?

In Germany, when another vehicle is overtaking you, you are required by law (§5 StVO) to make it as easy and safe as possible for the other driver. This means you must reduce your speed if it helps the overtaking vehicle to get back in safely, especially if the situation becomes tight or the overtaking driver needs to pull back in quicker than expected. Accelerating or increasing your speed during the overtaking maneuver is not allowed, as it can make the situation dangerous. Maintaining your speed is allowed only if it is clear that there is sufficient distance and no risk to the overtaking vehicle. In the scenario described, reducing speed so the overtaking vehicle can move in ahead of you is the safest and legally correct response. Always be attentive to traffic behind you and ready to adjust your speed to support safety during overtaking situations.