Something wrong with my boyfriends penis

Ye

My boyfriend’s penis bends unnaturally in some positions during sex. For example when I’m on top or some side angles and also basically every standing position.. it is fine when we do missionary or when I’m on my back. When it happens, it bends so much that it hurts and it’s not possible to keep going. When he’s hard, his penis is very straight so I don’t know why it happens. Anyone have any ideas?