IkePri idea: Belle returns to normal life, but the King "treats" her to time in the palace.
A couple of posts helped with this idea. One was Scummy talking about MC marrying someone but Gilbert keeping her at the palace for a month with lots of fucking. Another was a response to that saying men would give their wives to kings because it earned them favor. And then my usual thirsty self just wanting some angst and star-crossed romance.
So, Belle picks the king and goes home. They did fall in love, but in this idea they stuck with Clause 99. Time passes, maybe years, and MC marries someone else. Life has to go on. Love can grow even without the previous love fading away.
The current king makes a public appearance. Maybe on Bloodstained Rose Day when they do their ceremony. And MC attends because it's what any proud citizen would do. It's easy for him to pick her out of the crowd. It's easy to fall back into the obsessive desire to want to know how she's doing and what's going on in her life and if she still loves him. And it's easy to find her home address and have someone pay her and her husband a visit.
"The King would like to extend an invitation to the missus of the house."
Who would say no to that? The King wants to host MC for a time at the palace. Every compensation will be made for her absence, plus a generous donation or trade agreement or purchase or whatever MC's husband's work is. Yes, everyone knows you're being bought. But this is HUGE for a commoner. You're not even lesser nobility. Somehow you caught his eye.
Except you already know. And he already knows. And no one else does.
And now you get to go to the palace and have a secret romance with the most powerful man in the country, the both of you married to someone else, and it won't last. It can't. You will eventually return home.