Sorry if this is in the wrong format. This is only the third time I've used reddit for anything.
Honestly, I cannot remember the name of this manhwa I read a few months ago.
So, here's a quick summary of the plot. Noble FL is forcibly engaged to marry a higher ranking noble ML who lives in Far Off Land who had several previous wives/wife candidates die. Before the wedding, she is sent some jewelry. One piece has a special crystal and when she wears it, she's dragged to Hell. She spends X amount of time there, getting her butt kicked by low level demons before she gets sick of it and starts fighting back, with every demon she kills giving her more and more of these mysterious demon crystals, like the one in the piece of jewelry that brought her there. She finds out these crystals make her more powerful somehow, magical demon macguffin. Eventually she becomes hella strong (no pun intended) and she's just about to get some super important information to the plot before then suddenly being returned back to her body, before the engagement with ML. The engagement still happens but this time, she's training her formerly weak body back to what it was in Hell and this gets the ML's attention (among other things, I'm sure).
If that's too vague, I remember a scene where the FL and ML first meet in person at these standing stones sacred site kinda place to make sure neither of them are actually demons disguised as humans or something? I remember the FL had red hair and maybe gold eyes? (Like that's going to narrow it down at all.)
Thanks for your time!