To what extent does Léon and Rodolphe contributes to Emma's demise in Madame Bovary

I don't see Leon's character as having a part in her demise at all. He is completely dominated by his lover, even when he isn't sure about their relationship. Emma holds the cards and dictates their lives. He plays a role of submission.

Rodolphe, unlike Leon, isn't submissive. He becomes bored with Emma in the same way she becomes bored with marriage. Her affairs are very much a reaction to boredom.... men make her feel beautiful and wanted, she enjoys their adoration, but sooner or later the romantic aspext wears off, and she sees her lovers in the same way she sees her husband. Podolphe doesn't give her the time she needs to tire of him, as he tires of her first. Possibly this had a part in her decision to take her own life.... but maybe not.