When you've been together with someone for long enough, you kind of talk like you're married, and you have the rapport that suggests you're married, and you basically just give off those vibes time and time again — so they'll likely just assume that you're married.
And how my remaining days are meaningless! You only use the bathroom when you know they won't know what you're doing, or perhaps you go so far as to holding certain functions in when your partner is present.
Not only the drama finished with a huge cliffhanger but the leads were pretty much strangers in the end.