Peyronie's disease is a penile connective tissue illness similar to Dupuytren's contracture of the hand. Know more from here.
Peyronie's disease is most likely triggered by a small penile injury. This sort of injury is most commonly caused by forceful intercourse, although it can also be caused by sports or other incidents.
The penis's curvature is due to the presence of scar tissue beneath the skin. There is no known cause of scar tissue. Know more from here
In time, when the scar tissue hardens into a plaque, it causes a curvature of the penis shaft, which makes it less elastic than the rest of it.
When your penis grows erect, things begin to become uncomfortable for both you and your partner, making intercourse more difficult for you both.
There is no treatment for Peyronie's disease, although the modifications in the penis may always be improved. Stretch therapy (traction), medicines, and perhaps surgery are all options.