How do you tell someone that you will probably end up marrying them, but in a casual way?

Commentary:
๐Ÿค”๐Ÿ’ "So, like, at some point in the future, we might just accidentally start planning a wedding together… NBD, right? ๐Ÿ˜„๐Ÿ‘ฐ๐Ÿคต #CasualProposal"