You should (or better not) see my english two years ago, it was terrible.

Jeyne wasn't bad person, but she and Robb, it just wasn't working. No chemistry between them. I think he married her because he was his father's son - he had to. He made a mistake that night and had to live (then, well, not) with its consequences. I think she loved him, but couldn't understand she married a wolf. And he was trying to love her.

Yes, the Targaryens married their sisters/brothers. Marrying cousins - nothing strange. Cross-generational incest happened. But look at the Lannisters and all the fuss. And their family lived closer to the King's Landing. And the North was the biggest kingdom, still into old ways and old gods.

I love what Richard Madden said about them:
Him and Jon Snow have a fantastic relationship. They’ve grown up as brothers and they’ve dealt with everything together, especially in a world where men don’t share their emotions and don’t talk to each other and it’s just-that’s when you need Jon the most and that’s where he loses John. He loses his support.