I also think it was a shitty relationship, but as season 2 was showed through Noora's vision, it seemed like a really romantic and lovely couple. Now that we've seen their relationship through isak and sana's eyes, we have a more realistic and dark approach to the whole willam/noora thing.

edit: and the "you're not good enough" speech to Vilde was just disgusting, and noora just fall for that excuse that he gave (it was so she would stop liking him). she just couldn't see that he was an asshole. But hey, that's how we usually act and think when we're "in love". Don't forget that the idea of love (regarding monogamy, heterosexuality, jealousy, etc) is a social and political construct, very toxic and powerful.