I've changed my mind

My S/O is a strong believer in marriage. I wasn't. But everyday spent with this man just makes me fall more in love with him than the day before. He has known my feelings on marriage since before we were together but now I think I've had a serious change of heart. I've never felt this strongly about anyone before him. I want to tell him he has changed my heart and that Marriage is an option Now but IDK how to bring it up.