Adult Regency Romance, Intrigue. Titled gentleman and heroine not of same social circle, tension due to lack of trust. He tries to solve a mystery/ treachery. Ending described below... Read around 2020-2022. Spoiler.

[Chris]

I know it goes a long shot, since I remember only the ending well and the rest is just a blur, but here it goes..

hero is a titled gentleman (possibly a duke), the heroine is not part of the same social circle; there is some tension between the two, due lack of trust.
the hero tries to solve a mystery/treachery;
at the end there is a fight between the hero and the villain and the heroine arrives unexpectedly at the scene. A shot goes wild and the heroine gets hit, but due to shock does not realize it right away. She is pale and faints in the arms of the hero. Later on, the hero tells the heroine that she only survived, because she was wearing a fishbone-corset. She heals and the couple gets their happy ending.

I know it is not much to go by, but maybe it will ring a bell with someone.
I read the book around 2020-2022

The plot is in general similar to following:
An Inconvenient Duke by Anna Harrington
The Duke who knew to much by Grace Callaway
Heatless Duke Scarlett Scott
Thanks!

[Lobstergirl, au gratin]

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[Kris]

Chris, I copied some book details to the topic header. Feel free to edit it.

Do you recall how the couple first meets?
Does she had a paid job? Is he considered a rake?

Set in London?