It's all Andrei's fault.

We interrupt this silence for a very important PSA: 

Dear world, it's all Andrei's fault, and he should be the one apologising, not Natasha.

1. He set her up for failure: to "test one's love" is a ridiculous concept, have we learnt nothing from the story of Lothario and Antonio? (Yes, I am still struggling through Don Quixote, but I got past that bit at least). If you make it ridiculously difficult for someone to be faithful, you'll have gained nothing if they remain faithful, and lost everything if, like the human people they are, they fail. 

2. She needed to feel loved (because she is a normal human being). Going away is not a great way to show your love. 

3. I refuse the "it's all the father's fault" argument, Andrei was of age, he could marry whoever he wanted. Not obeying his father would not have lead to Andrei being disinherited, because that would go against his principles. So really, all he was risking was his father getting all grumpy at him, and let's face it, he already was. (Besides, Andrei needed to stay to protect Marya. I love Marya, she's great, so that, as well, is all Andrei's fault).

If you are very confused by this post, I am talking about War and Peace. There is a fantastic BBC adaptation of it running right now, and I may have got *slightly* too emotionally involved. Now you go watch it, and come back to agree with me that it's all Andrei's fault. Because it is.