Well, usually adaptations of manga can have differences like changes in the art style, the order of events, or sometimes added or removed subplots. For 'A Villains Circumstances' manga, it could be any of these or a combination.
Yes, there are many. For example, 'Fruits Basket' involves elements of family, relationships, and some aspects related to marriage in a very heart - warming and unique way. It focuses on the story of a girl who gets involved with a family cursed by the Chinese zodiac animals.
Sure. 'My Happy Marriage' was adapted from a manga. The adaptation tries to stay true to the original source material while bringing the story to life on the screen.