Did your SO Change After Engagement?

My boyfriend got engaged a couple years ago to his ex. And he said the moment after he proposed she changed. In a bad way. She was really controlling and made him clean and cook everything. Which led to their breakup. Me and my boyfriend have been together for a little bit now and he's been hinting at me that he might want to propose to me soon.. but I'm nervous he might change? I've heard so many stories about people changing after marriage or engagement. and I just want to know if that's true or not.