I want to know too please! Ty!
Sorry after reading your description again i realized it's not, just similar
https://www.mangago.me/read-manga/the_duchess_with_an_empty_soul/
Her husband cheats on her with her male cousin
It's not that one but thank you. The one I'm talking about, the one she loved was a knight and the guy he was cheating with was a close friend of hers. He had an actual high ranking job in the castle too and he wore glasses
Ohh, it's really different. Sorry but nothing comes to mind according to the info. Hope you'll be able to find it. Or if i come across it in the future, i will notify you
She finds out that her man is having an affair with her best friend (who is also a man) and I think she's reborn? It's one of the novel setting manhuas. Please please please help.