I found this in a forest in Karlsruhe (Germany).
The blooms are pink and have 5 leaves. Each leave is divided into two parts. It is pink and has a diameter of about 1-2cm.
It looks like a Red Campion, which is native to northern and central Europe.
It would be nice to see a close-up of the calyx (which is usually striped) and the leaves to be sure; it may be a cross between a White and Red Campion.
There are many members of the genus, and many look alike. Your close-up is of a male flower (anthers only). The plants are male or female.
Looks kind of like a species in the genus Silene. Interesting group, I believe some species in this group are dioecious and have sex chromosomes.